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freebsd-dev/gnu/usr.bin/as/config/tc-tahoe.c

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/* tc-tahoe.c
Not part of GAS yet. */
#include "as.h"
#include "obstack.h"
/* this bit glommed from tahoe-inst.h */
typedef unsigned char byte;
typedef byte tahoe_opcodeT;
/*
* This is part of tahoe-ins-parse.c & friends.
* We want to parse a tahoe instruction text into a tree defined here.
*/
#define TIT_MAX_OPERANDS (4) /* maximum number of operands in one
single tahoe instruction */
struct top /* tahoe instruction operand */
{
int top_ndx; /* -1, or index register. eg 7=[R7] */
int top_reg; /* -1, or register number. eg 7 = R7 or (R7) */
byte top_mode; /* Addressing mode byte. This byte, defines
which of the 11 modes opcode is. */
char top_access; /* Access type wanted for this opperand
'b'branch ' 'no-instruction 'amrvw' */
char top_width; /* Operand width expected, one of "bwlq?-:!" */
char *top_error; /* Say if operand is inappropriate */
expressionS exp_of_operand; /* The expression as parsed by expression()*/
byte top_dispsize; /* Number of bytes in the displacement if we
can figure it out */
};
/* The addressing modes for an operand. These numbers are the acutal values
for certain modes, so be carefull if you screw with them. */
#define TAHOE_DIRECT_REG (0x50)
#define TAHOE_REG_DEFERRED (0x60)
#define TAHOE_REG_DISP (0xE0)
#define TAHOE_REG_DISP_DEFERRED (0xF0)
#define TAHOE_IMMEDIATE (0x8F)
#define TAHOE_IMMEDIATE_BYTE (0x88)
#define TAHOE_IMMEDIATE_WORD (0x89)
#define TAHOE_IMMEDIATE_LONGWORD (0x8F)
#define TAHOE_ABSOLUTE_ADDR (0x9F)
#define TAHOE_DISPLACED_RELATIVE (0xEF)
#define TAHOE_DISP_REL_DEFERRED (0xFF)
#define TAHOE_AUTO_DEC (0x7E)
#define TAHOE_AUTO_INC (0x8E)
#define TAHOE_AUTO_INC_DEFERRED (0x9E)
/* INDEXED_REG is decided by the existance or lack of a [reg] */
/* These are encoded into top_width when top_access=='b'
and it's a psuedo op.*/
#define TAHOE_WIDTH_ALWAYS_JUMP '-'
#define TAHOE_WIDTH_CONDITIONAL_JUMP '?'
#define TAHOE_WIDTH_BIG_REV_JUMP '!'
#define TAHOE_WIDTH_BIG_NON_REV_JUMP ':'
/* The hex code for certain tahoe commands and modes.
This is just for readability. */
#define TAHOE_JMP (0x71)
#define TAHOE_PC_REL_LONG (0xEF)
#define TAHOE_BRB (0x11)
#define TAHOE_BRW (0x13)
/* These, when 'ored' with, or added to, a register number,
set up the number for the displacement mode. */
#define TAHOE_PC_OR_BYTE (0xA0)
#define TAHOE_PC_OR_WORD (0xC0)
#define TAHOE_PC_OR_LONG (0xE0)
struct tit /* get it out of the sewer, it stands for
tahoe instruction tree (Geeze!) */
{
tahoe_opcodeT tit_opcode; /* The opcode. */
byte tit_operands; /* How many operands are here. */
struct top tit_operand[TIT_MAX_OPERANDS]; /* Operands */
char *tit_error; /* "" or fatal error text */
};
/* end: tahoe-inst.h */
/* tahoe.c - tahoe-specific -
Not part of gas yet.
*/
#include "opcode/tahoe.h"
/* This is the number to put at the beginning of the a.out file */
long omagic = OMAGIC;
/* These chars start a comment anywhere in a source file (except inside
another comment or a quoted string. */
const char comment_chars[] = "#;";
/* These chars only start a comment at the beginning of a line. */
const char line_comment_chars[] = "#";
/* Chars that can be used to separate mant from exp in floating point nums */
const char EXP_CHARS[] = "eE";
/* Chars that mean this number is a floating point constant
as in 0f123.456
or 0d1.234E-12 (see exp chars above)
Note: The Tahoe port doesn't support floating point constants. This is
consistant with 'as' If it's needed, I can always add it later. */
const char FLT_CHARS[] = "df";
/* Also be aware that MAXIMUM_NUMBER_OF_CHARS_FOR_FLOAT may have to be
changed in read.c . Ideally it shouldn't have to know about it at all,
but nothing is ideal around here.
(The tahoe has plenty of room, so the change currently isn't needed.)
*/
static struct tit t; /* A tahoe instruction after decoding. */
void float_cons ();
/* A table of pseudo ops (sans .), the function called, and an integer op
that the function is called with. */
const pseudo_typeS md_pseudo_table[] =
{
{"dfloat", float_cons, 'd'},
{"ffloat", float_cons, 'f'},
{0}
};
/*
* For Tahoe, relative addresses of "just the right length" are pretty easy.
* The branch displacement is always the last operand, even in
* synthetic instructions.
* For Tahoe, we encode the relax_substateTs (in e.g. fr_substate) as:
*
* 4 3 2 1 0 bit number
* ---/ /--+-------+-------+-------+-------+-------+
* | what state ? | how long ? |
* ---/ /--+-------+-------+-------+-------+-------+
*
* The "how long" bits are 00=byte, 01=word, 10=long.
* This is a Un*x convention.
* Not all lengths are legit for a given value of (what state).
* The four states are listed below.
* The "how long" refers merely to the displacement length.
* The address usually has some constant bytes in it as well.
*
States for Tahoe address relaxing.
1. TAHOE_WIDTH_ALWAYS_JUMP (-)
Format: "b-"
Tahoe opcodes are: (Hex)
jr 11
jbr 11
Simple branch.
Always, 1 byte opcode, then displacement/absolute.
If word or longword, change opcode to brw or jmp.
2. TAHOE_WIDTH_CONDITIONAL_JUMP (?)
J<cond> where <cond> is a simple flag test.
Format: "b?"
Tahoe opcodes are: (Hex)
jneq/jnequ 21
jeql/jeqlu 31
jgtr 41
jleq 51
jgeq 81
jlss 91
jgtru a1
jlequ b1
jvc c1
jvs d1
jlssu/jcs e1
jgequ/jcc f1
Always, you complement 4th bit to reverse the condition.
Always, 1-byte opcode, then 1-byte displacement.
3. TAHOE_WIDTH_BIG_REV_JUMP (!)
Jbc/Jbs where cond tests a memory bit.
Format: "rlvlb!"
Tahoe opcodes are: (Hex)
jbs 0e
jbc 1e
Always, you complement 4th bit to reverse the condition.
Always, 1-byte opcde, longword, longword-address, 1-word-displacement
4. TAHOE_WIDTH_BIG_NON_REV_JUMP (:)
JaoblXX/Jbssi
Format: "rlmlb:"
Tahoe opcodes are: (Hex)
aojlss 2f
jaoblss 2f
aojleq 3f
jaobleq 3f
jbssi 5f
Always, we cannot reverse the sense of the branch; we have a word
displacement.
We need to modify the opcode is for class 1, 2 and 3 instructions.
After relax() we may complement the 4th bit of 2 or 3 to reverse sense of
branch.
We sometimes store context in the operand literal. This way we can figure out
after relax() what the original addressing mode was. (Was is pc_rel, or
pc_rel_disp? That sort of thing.) */
/* These displacements are relative to the START address of the
displacement which is at the start of the displacement, not the end of
the instruction. The hardware pc_rel is at the end of the instructions.
That's why all the displacements have the length of the displacement added
to them. (WF + length(word))
The first letter is Byte, Word.
2nd letter is Forward, Backward. */
#define BF (1+ 127)
#define BB (1+-128)
#define WF (2+ 32767)
#define WB (2+-32768)
/* Dont need LF, LB because they always reach. [They are coded as 0.] */
#define C(a,b) ENCODE_RELAX(a,b)
/* This macro has no side-effects. */
#define ENCODE_RELAX(what,length) (((what) << 2) + (length))
#define RELAX_STATE(what) ((what) >> 2)
#define RELAX_LENGTH(length) ((length) && 3)
#define STATE_ALWAYS_BRANCH (1)
#define STATE_CONDITIONAL_BRANCH (2)
#define STATE_BIG_REV_BRANCH (3)
#define STATE_BIG_NON_REV_BRANCH (4)
#define STATE_PC_RELATIVE (5)
#define STATE_BYTE (0)
#define STATE_WORD (1)
#define STATE_LONG (2)
#define STATE_UNDF (3) /* Symbol undefined in pass1 */
/* This is the table used by gas to figure out relaxing modes. The fields are
forward_branch reach, backward_branch reach, number of bytes it would take,
where the next biggest branch is. */
const relax_typeS
md_relax_table[] =
{
{
1, 1, 0, 0
}, /* error sentinel 0,0 */
{
1, 1, 0, 0
}, /* unused 0,1 */
{
1, 1, 0, 0
}, /* unused 0,2 */
{
1, 1, 0, 0
}, /* unused 0,3 */
/* Unconditional branch cases "jrb"
The relax part is the actual displacement */
{
BF, BB, 1, C (1, 1)
}, /* brb B`foo 1,0 */
{
WF, WB, 2, C (1, 2)
}, /* brw W`foo 1,1 */
{
0, 0, 5, 0
}, /* Jmp L`foo 1,2 */
{
1, 1, 0, 0
}, /* unused 1,3 */
/* Reversible Conditional Branch. If the branch won't reach, reverse
it, and jump over a brw or a jmp that will reach. The relax part is the
actual address. */
{
BF, BB, 1, C (2, 1)
}, /* b<cond> B`foo 2,0 */
{
WF + 2, WB + 2, 4, C (2, 2)
}, /* brev over, brw W`foo, over: 2,1 */
{
0, 0, 7, 0
}, /* brev over, jmp L`foo, over: 2,2 */
{
1, 1, 0, 0
}, /* unused 2,3 */
/* Another type of reversable branch. But this only has a word
displacement. */
{
1, 1, 0, 0
}, /* unused 3,0 */
{
WF, WB, 2, C(3, 2)
}, /* jbX W`foo 3,1 */
{
0, 0, 8, 0
}, /* jrevX over, jmp L`foo, over: 3,2 */
{
1, 1, 0, 0
}, /* unused 3,3 */
/* These are the non reversable branches, all of which have a word
displacement. If I can't reach, branch over a byte branch, to a
jump that will reach. The jumped branch jumps over the reaching
branch, to continue with the flow of the program. It's like playing
leap frog. */
{
1, 1, 0, 0
}, /* unused 4,0 */
{
WF, WB, 2, C (4, 2)
}, /* aobl_ W`foo 4,1 */
{
0, 0, 10, 0
}, /*aobl_ W`hop,br over,hop: jmp L^foo,over 4,2*/
{
1, 1, 0, 0
}, /* unused 4,3 */
/* Normal displacement mode, no jumping or anything like that.
The relax points to one byte before the address, thats why all
the numbers are up by one. */
{
BF + 1, BB + 1, 2, C (5, 1)
}, /* B^"foo" 5,0 */
{
WF + 1, WB + 1, 3, C (5, 2)
}, /* W^"foo" 5,1 */
{
0, 0, 5, 0
}, /* L^"foo" 5,2 */
{
1, 1, 0, 0
}, /* unused 5,3 */
};
#undef C
#undef BF
#undef BB
#undef WF
#undef WB
/* End relax stuff */
static struct hash_control *op_hash = NULL; /* handle of the OPCODE hash table
NULL means any use before md_begin() will
crash */
/* Init function. Build the hash table. */
void
md_begin()
{
struct tot *tP;
char *errorval = "";
int synthetic_too = 1; /* If 0, just use real opcodes. */
if ((op_hash = hash_new())){
for (tP= totstrs; *tP->name && !*errorval; tP++){
errorval = hash_insert (op_hash, tP->name, &tP->detail);
}
if (synthetic_too){
for (tP = synthetic_totstrs; *tP->name && !*errorval; tP++){
errorval = hash_insert (op_hash, tP->name, &tP->detail);
}
}
}else{
errorval = "Virtual memory exceeded";
}
if (*errorval)
as_fatal(errorval);
}/* md_begin */
void
md_end()
{
}/* md_end */
int
md_parse_option (argP, cntP, vecP)
char **argP;
int *cntP;
char ***vecP;
{
char *temp_name; /* name for -t or -d options */
char opt;
switch (**argP){
case 'a':
as_warn("The -a option doesn't exits. (Dispite what the man page says!");
case 'J':
as_warn("JUMPIFY (-J) not implemented, use psuedo ops instead.");
break;
case 'S':
as_warn ("SYMBOL TABLE not implemented");
break; /* SYMBOL TABLE not implemented */
case 'T':
as_warn ("TOKEN TRACE not implemented");
break; /* TOKEN TRACE not implemented */
case 'd':
case 't':
opt= **argP;
if (**argP){ /* Rest of argument is filename. */
temp_name = *argP;
while (**argP)
(*argP)++;
}else if (*cntP){
while (**argP)
(*argP)++;
--(*cntP);
temp_name = *++(*vecP);
**vecP = NULL; /* Remember this is not a file-name. */
}else{
as_warn ("I expected a filename after -%c.",opt);
temp_name = "{absent}";
}
if(opt=='d')
as_warn ("Displacement length %s ignored!", temp_name);
else
as_warn ("I don't need or use temp. file \"%s\".", temp_name);
break;
case 'V':
as_warn ("I don't use an interpass file! -V ignored");
break;
default:
return 0;
}
return 1;
}
/* The functions in this section take numbers in the machine format, and
munges them into Tahoe byte order.
They exist primarily for cross assembly purpose. */
void /* Knows about order of bytes in address. */
md_number_to_chars (con, value, nbytes)
char con[]; /* Return 'nbytes' of chars here. */
long int value; /* The value of the bits. */
int nbytes; /* Number of bytes in the output. */
{
int n = nbytes;
long int v = value;
con += nbytes - 1; /* Tahoes is (Bleah!) big endian */
while (nbytes--){
*con-- = value; /* Lint wants & MASK_CHAR. */
value >>= BITS_PER_CHAR;
}
/* XXX line number probably botched for this warning message. */
if (value != 0 && value != -1)
as_warn ("Displacement (%ld) long for instruction field length (%d).",v,n);
}
#ifdef comment
void /* Knows about order of bytes in address. */
md_number_to_imm (con, value, nbytes)
char con[]; /* Return 'nbytes' of chars here. */
long int value; /* The value of the bits. */
int nbytes; /* Number of bytes in the output. */
{
md_number_to_chars(con, value, nbytes);
}
#endif /* comment */
void
md_apply_fix(fixP, val)
fixS *fixP;
long val;
{
char *place = fixP->fx_where + fixP->fx_frag->fr_literal;
md_number_to_chars(place, val, fixP->fx_size);
return;
} /* md_apply_fix() */
void /* Knows about order of bytes in address. */
md_number_to_disp (con, value, nbytes)
char con[]; /* Return 'nbytes' of chars here. */
long int value; /* The value of the bits. */
int nbytes; /* Number of bytes in the output. */
{
md_number_to_chars(con, value, nbytes);
}
void /* Knows about order of bytes in address. */
md_number_to_field (con, value, nbytes)
char con[]; /* Return 'nbytes' of chars here. */
long int value; /* The value of the bits. */
int nbytes; /* Number of bytes in the output. */
{
md_number_to_chars(con, value, nbytes);
}
/* Put the bits in an order that a tahoe will understand, despite the ordering
of the native machine.
On Tahoe: first 4 bytes are normal unsigned big endian long,
next three bytes are symbolnum, in kind of 3 byte big endian (least sig. byte last).
The last byte is broken up with bit 7 as pcrel,
bits 6 & 5 as length,
bit 4 as extern and the last nibble as 'undefined'. */
#if comment
void
md_ri_to_chars (ri_p, ri)
struct relocation_info *ri_p, ri;
{
byte the_bytes[sizeof(struct relocation_info)];
/* The reason I can't just encode these directly into ri_p is that
ri_p may point to ri. */
/* This is easy */
md_number_to_chars (the_bytes, ri.r_address, sizeof(ri.r_address));
/* now the fun stuff */
the_bytes[4] = (ri.r_symbolnum >> 16) & 0x0ff;
the_bytes[5] = (ri.r_symbolnum >> 8) & 0x0ff;
the_bytes[6] = ri.r_symbolnum & 0x0ff;
the_bytes[7] = (((ri.r_extern << 4) & 0x10) | ((ri.r_length << 5) & 0x60) |
((ri.r_pcrel << 7) & 0x80)) & 0xf0;
bcopy (the_bytes, (char *) ri_p, sizeof (struct relocation_info));
}
#endif /* comment */
/* Put the bits in an order that a tahoe will understand, despite the ordering
of the native machine.
On Tahoe: first 4 bytes are normal unsigned big endian long,
next three bytes are symbolnum, in kind of 3 byte big endian (least sig. byte last).
The last byte is broken up with bit 7 as pcrel,
bits 6 & 5 as length,
bit 4 as extern and the last nibble as 'undefined'. */
void tc_aout_fix_to_chars(where, fixP, segment_address_in_file)
char *where;
fixS *fixP;
relax_addressT segment_address_in_file;
{
/*
* In: length of relocation (or of address) in chars: 1, 2 or 4.
* Out: GNU LD relocation length code: 0, 1, or 2.
*/
static unsigned char nbytes_r_length[] = { 42, 0, 1, 42, 2 };
long r_symbolnum;
know(fixP->fx_addsy != NULL);
md_number_to_chars(where,
fixP->fx_frag->fr_address + fixP->fx_where - segment_address_in_file,
4);
r_symbolnum = (S_IS_DEFINED(fixP->fx_addsy)
? S_GET_TYPE(fixP->fx_addsy)
: fixP->fx_addsy->sy_number);
where[4] = (r_symbolnum >> 16) & 0x0ff;
where[5] = (r_symbolnum >> 8) & 0x0ff;
where[6] = r_symbolnum & 0x0ff;
where[7] = (((fixP->fx_pcrel << 7) & 0x80)
| ((nbytes_r_length[fixP->fx_size] << 5) & 0x60)
| ((!S_IS_DEFINED(fixP->fx_addsy) << 4) & 0x10));
return;
} /* tc_aout_fix_to_chars() */
/* Relocate byte stuff */
/* This is for broken word. */
const int md_short_jump_size = 3;
void
md_create_short_jump (ptr, from_addr, to_addr, frag, to_symbol)
char *ptr;
long from_addr, to_addr;
fragS *frag;
symbolS *to_symbol;
{
long offset;
offset = to_addr - (from_addr + 1);
*ptr++ = TAHOE_BRW;
md_number_to_chars (ptr, offset, 2);
}
const int md_long_jump_size = 6;
const int md_reloc_size = 8; /* Size of relocation record */
void
md_create_long_jump (ptr, from_addr, to_addr, frag, to_symbol)
char *ptr;
long from_addr, to_addr;
fragS *frag;
symbolS *to_symbol;
{
long offset;
offset = to_addr - (from_addr + 4);
*ptr++ = TAHOE_JMP;
*ptr++ = TAHOE_PC_REL_LONG;
md_number_to_chars (ptr, offset, 4);
}
/*
* md_estimate_size_before_relax()
*
* Called just before relax().
* Any symbol that is now undefined will not become defined, so we assumed
* that it will be resolved by the linker.
* Return the correct fr_subtype in the frag, for relax()
* Return the initial "guess for fr_var" to caller. (How big I think this
* will be.)
* The guess for fr_var is ACTUALLY the growth beyond fr_fix.
* Whatever we do to grow fr_fix or fr_var contributes to our returned value.
* Although it may not be explicit in the frag, pretend fr_var starts with a
* 0 value.
*/
int
md_estimate_size_before_relax (fragP, segment_type)
register fragS *fragP;
segT segment_type; /* N_DATA or N_TEXT. */
{
register char *p;
register int old_fr_fix;
/* int pc_rel; FIXME: remove this */
old_fr_fix = fragP->fr_fix;
switch (fragP->fr_subtype){
case ENCODE_RELAX (STATE_PC_RELATIVE, STATE_UNDF):
if (S_GET_SEGMENT(fragP->fr_symbol) == segment_type) {
/* The symbol was in the same segment as the opcode, and it's
a real pc_rel case so it's a relaxable case. */
fragP->fr_subtype = ENCODE_RELAX(STATE_PC_RELATIVE, STATE_BYTE);
}else{
/* This case is still undefined, so asume it's a long word for the
linker to fix. */
p = fragP->fr_literal + old_fr_fix;
*p |= TAHOE_PC_OR_LONG;
/* We now know how big it will be, one long word. */
fragP->fr_fix += 1 + 4;
fix_new (fragP, old_fr_fix + 1, 4, fragP->fr_symbol, 0,
fragP->fr_offset, 1, NO_RELOC);
frag_wane (fragP);
}
break;
case ENCODE_RELAX (STATE_CONDITIONAL_BRANCH, STATE_UNDF):
if (S_GET_SEGMENT(fragP->fr_symbol) == segment_type){
fragP->fr_subtype = ENCODE_RELAX (STATE_CONDITIONAL_BRANCH, STATE_BYTE);
}else{
p = fragP->fr_literal + old_fr_fix;
*fragP->fr_opcode ^= 0x10; /* Reverse sense of branch. */
*p++ = 6;
*p++ = TAHOE_JMP;
*p++ = TAHOE_PC_REL_LONG;
fragP->fr_fix += 1 + 1 + 1 + 4;
fix_new (fragP, old_fr_fix + 3, 4, fragP->fr_symbol, 0,
fragP->fr_offset, 1, NO_RELOC);
frag_wane (fragP);
}
break;
case ENCODE_RELAX (STATE_BIG_REV_BRANCH, STATE_UNDF):
if (S_GET_SEGMENT(fragP->fr_symbol) == segment_type){
fragP->fr_subtype =
ENCODE_RELAX (STATE_BIG_REV_BRANCH, STATE_WORD);
}else{
p = fragP->fr_literal + old_fr_fix;
*fragP->fr_opcode ^= 0x10; /* Reverse sense of branch. */
*p++ = 0;
*p++ = 6;
*p++ = TAHOE_JMP;
*p++ = TAHOE_PC_REL_LONG;
fragP->fr_fix += 2 + 2 + 4;
fix_new (fragP, old_fr_fix + 4, 4, fragP->fr_symbol, 0,
fragP->fr_offset, 1, NO_RELOC);
frag_wane (fragP);
}
break;
case ENCODE_RELAX (STATE_BIG_NON_REV_BRANCH, STATE_UNDF):
if (S_GET_SEGMENT(fragP->fr_symbol) == segment_type){
fragP->fr_subtype = ENCODE_RELAX (STATE_BIG_NON_REV_BRANCH, STATE_WORD);
}else{
p = fragP->fr_literal + old_fr_fix;
*p++ = 2;
*p++ = 0;
*p++ = TAHOE_BRB;
*p++ = 6;
*p++ = TAHOE_JMP;
*p++ = TAHOE_PC_REL_LONG;
fragP->fr_fix += 2 + 2 + 2 + 4;
fix_new (fragP, old_fr_fix + 6, 4, fragP->fr_symbol, 0,
fragP->fr_offset, 1, NO_RELOC);
frag_wane (fragP);
}
break;
case ENCODE_RELAX (STATE_ALWAYS_BRANCH, STATE_UNDF):
if (S_GET_SEGMENT(fragP->fr_symbol) == segment_type){
fragP->fr_subtype = ENCODE_RELAX (STATE_ALWAYS_BRANCH, STATE_BYTE);
}else{
p = fragP->fr_literal + old_fr_fix;
*fragP->fr_opcode = TAHOE_JMP;
*p++ = TAHOE_PC_REL_LONG;
fragP->fr_fix += 1 + 4;
fix_new (fragP, old_fr_fix + 1, 4, fragP->fr_symbol, 0,
fragP->fr_offset, 1, NO_RELOC);
frag_wane (fragP);
}
break;
default:
break;
}
return (fragP->fr_var + fragP->fr_fix - old_fr_fix);
} /* md_estimate_size_before_relax() */
/*
* md_convert_frag();
*
* Called after relax() is finished.
* In: Address of frag.
* fr_type == rs_machine_dependent.
* fr_subtype is what the address relaxed to.
*
* Out: Any fixSs and constants are set up.
* Caller will turn frag into a ".space 0".
*/
void
md_convert_frag (headers, fragP)
object_headers *headers;
register fragS *fragP;
{
register char *addressP; /* -> _var to change. */
register char *opcodeP; /* -> opcode char(s) to change. */
register short int length_code; /* 2=long 1=word 0=byte */
register short int extension = 0; /* Size of relaxed address.
Added to fr_fix: incl. ALL var chars. */
register symbolS *symbolP;
register long int where;
register long int address_of_var;
/* Where, in file space, is _var of *fragP? */
register long int target_address;
/* Where, in file space, does addr point? */
know (fragP->fr_type == rs_machine_dependent);
length_code = RELAX_LENGTH(fragP->fr_subtype);
know (length_code >= 0 && length_code < 3);
where = fragP->fr_fix;
addressP = fragP->fr_literal + where;
opcodeP = fragP->fr_opcode;
symbolP = fragP->fr_symbol;
know(symbolP);
target_address = S_GET_VALUE(symbolP) + fragP->fr_offset;
address_of_var = fragP->fr_address + where;
switch (fragP->fr_subtype){
case ENCODE_RELAX(STATE_PC_RELATIVE, STATE_BYTE):
/* *addressP holds the registers number, plus 0x10, if it's deferred
mode. To set up the right mode, just OR the size of this displacement */
/* Byte displacement. */
*addressP++ |= TAHOE_PC_OR_BYTE;
*addressP = target_address - (address_of_var + 2);
extension = 2;
break;
case ENCODE_RELAX(STATE_PC_RELATIVE, STATE_WORD):
/* Word displacement. */
*addressP++ |= TAHOE_PC_OR_WORD;
md_number_to_chars(addressP, target_address - (address_of_var + 3), 2);
extension = 3;
break;
case ENCODE_RELAX (STATE_PC_RELATIVE, STATE_LONG):
/* Long word displacement. */
*addressP++ |= TAHOE_PC_OR_LONG;
md_number_to_chars(addressP, target_address - (address_of_var + 5), 4);
extension = 5;
break;
case ENCODE_RELAX (STATE_CONDITIONAL_BRANCH, STATE_BYTE):
*addressP = target_address - (address_of_var + 1);
extension = 1;
break;
case ENCODE_RELAX (STATE_CONDITIONAL_BRANCH, STATE_WORD):
*opcodeP ^= 0x10; /* Reverse sense of test. */
*addressP++ = 3; /* Jump over word branch */
*addressP++ = TAHOE_BRW;
md_number_to_chars (addressP, target_address - (address_of_var + 4), 2);
extension = 4;
break;
case ENCODE_RELAX (STATE_CONDITIONAL_BRANCH, STATE_LONG):
*opcodeP ^= 0x10; /* Reverse sense of test. */
*addressP++ = 6;
*addressP++ = TAHOE_JMP;
*addressP++ = TAHOE_PC_REL_LONG;
md_number_to_chars (addressP, target_address, 4);
extension = 7;
break;
case ENCODE_RELAX (STATE_ALWAYS_BRANCH, STATE_BYTE):
*addressP = target_address - (address_of_var + 1);
extension = 1;
break;
case ENCODE_RELAX (STATE_ALWAYS_BRANCH, STATE_WORD):
*opcodeP = TAHOE_BRW;
md_number_to_chars (addressP, target_address - (address_of_var + 2), 2);
extension = 2;
break;
case ENCODE_RELAX (STATE_ALWAYS_BRANCH, STATE_LONG):
*opcodeP = TAHOE_JMP;
*addressP++ = TAHOE_PC_REL_LONG;
md_number_to_chars(addressP, target_address - (address_of_var + 5), 4);
extension = 5;
break;
case ENCODE_RELAX (STATE_BIG_REV_BRANCH, STATE_WORD):
md_number_to_chars (addressP, target_address - (address_of_var + 2), 2);
extension = 2;
break;
case ENCODE_RELAX (STATE_BIG_REV_BRANCH, STATE_LONG):
*opcodeP ^= 0x10;
*addressP++ = 0;
*addressP++ = 6;
*addressP++ = TAHOE_JMP;
*addressP++ = TAHOE_PC_REL_LONG;
md_number_to_chars (addressP, target_address, 4);
extension = 8;
break;
case ENCODE_RELAX (STATE_BIG_NON_REV_BRANCH, STATE_WORD):
md_number_to_chars (addressP, target_address - (address_of_var + 2), 2);
extension = 2;
break;
case ENCODE_RELAX (STATE_BIG_NON_REV_BRANCH, STATE_LONG):
*addressP++ = 0;
*addressP++ = 2;
*addressP++ = TAHOE_BRB;
*addressP++ = 6;
*addressP++ = TAHOE_JMP;
*addressP++ = TAHOE_PC_REL_LONG;
md_number_to_chars (addressP, target_address, 4);
extension = 10;
break;
default:
BAD_CASE (fragP->fr_subtype);
break;
}
fragP->fr_fix += extension;
} /* md_convert_frag */
/* This is the stuff for md_assemble. */
#define FP_REG 13
#define SP_REG 14
#define PC_REG 15
#define BIGGESTREG PC_REG
/*
* Parse the string pointed to by START
* If it represents a valid register, point START to the character after
* the last valid register char, and return the register number (0-15).
* If invalid, leave START alone, return -1.
* The format has to be exact. I don't do things like eat leading zeros
* or the like.
* Note: This doesn't check for the next character in the string making
* this invalid. Ex: R123 would return 12, it's the callers job to check
* what start is point to apon return.
*
* Valid registers are R1-R15, %1-%15, FP (13), SP (14), PC (15)
* Case doesn't matter.
*/
int
tahoe_reg_parse(start)
char **start; /* A pointer to the string to parse. */
{
register char *regpoint = *start;
register int regnum = -1;
switch(*regpoint++){
case '%': /* Registers can start with a %,
R or r, and then a number. */
case 'R':
case 'r':
if (isdigit(*regpoint)){
/* Got the first digit. */
regnum = *regpoint++ - '0';
if ((regnum == 1) && isdigit(*regpoint)){
/* Its a two digit number. */
regnum = 10 + (*regpoint++ - '0');
if (regnum > BIGGESTREG){ /* Number too big? */
regnum = -1;
}
}
}
break;
case 'F': /* Is it the FP */
case 'f':
switch(*regpoint++){
case 'p':
case 'P':
regnum = FP_REG;
}
break;
case 's': /* How about the SP */
case 'S':
switch(*regpoint++){
case 'p':
case 'P':
regnum = SP_REG;
}
break;
case 'p': /* OR the PC even */
case 'P':
switch(*regpoint++){
case 'c':
case 'C':
regnum = PC_REG;
}
break;
}
if (regnum != -1){ /* No error, so move string pointer */
*start = regpoint;
}
return regnum; /* Return results */
} /* tahoe_reg_parse */
/*
* This chops up an operand and figures out its modes and stuff.
* It's a little touchy about extra characters.
* Optex to start with one extra character so it can be overwritten for
* the backward part of the parsing.
* You can't put a bunch of extra characters in side to
* make the command look cute. ie: * foo ( r1 ) [ r0 ]
* If you like doing a lot of typing, try COBOL!
* Actually, this parser is a little weak all around. It's designed to be
* used with compliers, so I emphisise correct decoding of valid code quickly
* rather that catching every possable error.
* Note: This uses the expression function, so save input_line_pointer before
* calling.
*
* Sperry defines the semantics of address modes (and values)
* by a two-letter code, explained here.
*
* letter 1: access type
*
* a address calculation - no data access, registers forbidden
* b branch displacement
* m read - let go of bus - write back "modify"
* r read
* w write
* v bit field address: like 'a' but registers are OK
*
* letter 2: data type (i.e. width, alignment)
*
* b byte
* w word
* l longword
* q quadword (Even regs < 14 allowed) (if 12, you get a warning)
* - unconditional synthetic jbr operand
* ? simple synthetic reversable branch operand
* ! complex synthetic reversable branch operand
* : complex synthetic non-reversable branch operand
*
* The '-?!:' letter 2's are not for external consumption. They are used
* by GAS for psuedo ops relaxing code.
*
* After parsing topP has:
*
* top_ndx: -1, or the index register. eg 7=[R7]
* top_reg: -1, or register number. eg 7 = R7 or (R7)
* top_mode: The addressing mode byte. This byte, defines which of
* the 11 modes opcode is.
* top_access: Access type wanted for this opperand 'b'branch ' '
* no-instruction 'amrvw'
* top_width: Operand width expected, one of "bwlq?-:!"
* exp_of_operand: The expression as parsed by expression()
* top_dispsize: Number of bytes in the displacement if we can figure it
* out and it's relavent.
*
* Need syntax checks built.
*/
void
tip_op (optex,topP)
char *optex; /* The users text input, with one leading character */
struct top *topP;/* The tahoe instruction with some fields already set:
in: access, width
out: ndx, reg, mode, error, dispsize */
{
int mode = 0; /* This operand's mode. */
char segfault = *optex; /* To keep the back parsing from freaking. */
char *point = optex+1; /* Parsing from front to back. */
char *end; /* Parsing from back to front. */
int reg = -1; /* major register, -1 means absent */
int imreg = -1; /* Major register in immediate mode */
int ndx = -1; /* index register number, -1 means absent */
char dec_inc = ' '; /* Is the SP auto-incremented '+' or
auto-decremented '-' or neither ' '. */
int immediate = 0; /* 1 if '$' immediate mode */
int call_width = 0; /* If the caller casts the displacement */
int abs_width = 0; /* The width of the absolute displacment */
int com_width = 0; /* Displacement width required by branch */
int deferred = 0; /* 1 if '*' deferral is used */
byte disp_size = 0; /* How big is this operand. 0 == don't know */
char *op_bad = ""; /* Bad operand error */
char *tp, *temp, c; /* Temporary holders */
char access = topP->top_access; /* Save on a deref. */
char width = topP->top_width;
int really_none = 0; /* Empty expressions evaluate to 0
but I need to know if it's there or not */
expressionS *expP; /* -> expression values for this operand */
/* Does this command restrict the displacement size. */
if (access == 'b')
com_width = (width == 'b' ? 1 :
(width == 'w' ? 2 :
(width == 'l' ? 4 : 0)));
*optex = '\0'; /* This is kind of a back stop for all
the searches to fail on if needed.*/
if (*point == '*') { /* A dereference? */
deferred = 1;
point++;
}
/* Force words into a certain mode */
/* Bitch, Bitch, Bitch! */
/*
* Using the ^ operator is ambigous. If I have an absolute label
* called 'w' set to, say 2, and I have the expression 'w^1', do I get
* 1, forced to be in word displacement mode, or do I get the value of
* 'w' or'ed with 1 (3 in this case).
* The default is 'w' as an offset, so that's what I use.
* Stick with `, it does the same, and isn't ambig.
*/
if (*point != '\0' && ((point[1] == '^') || (point[1] == '`')))
switch(*point){
case 'b':
case 'B':
case 'w':
case 'W':
case 'l':
case 'L':
if (com_width)
as_warn("Casting a branch displacement is bad form, and is ignored.");
else{
c = (isupper(*point) ? tolower(*point) : *point);
call_width = ((c == 'b') ? 1 :
((c == 'w') ? 2 : 4));
}
point += 2;
break;
}
/* Setting immediate mode */
if (*point == '$'){
immediate = 1;
point++;
}
/*
* I've pulled off all the easy stuff off the front, move to the end and
* yank.
*/
for(end = point;*end != '\0';end++) /* Move to the end. */
;
if(end != point) /* Null string? */
end--;
if (end > point && *end == ' ' && end[-1] != '\'')
end--; /* Hop white space */
/* Is this an index reg. */
if ((*end == ']') && (end[-1] != '\'')){
temp = end;
/* Find opening brace. */
for(--end;(*end != '[' && end != point);end--)
;
/* If I found the opening brace, get the index register number. */
if (*end == '['){
tp = end + 1; /* tp should point to the start of a reg. */
ndx = tahoe_reg_parse(&tp);
if (tp != temp){ /* Reg. parse error. */
ndx = -1;
} else {
end--; /* Found it, move past brace. */
}
if (ndx == -1){
op_bad = "Couldn't parse the [index] in this operand.";
end = point; /* Force all the rest of the tests to fail. */
}
}else{
op_bad = "Couldn't find the opening '[' for the index of this operand.";
end = point; /* Force all the rest of the tests to fail. */
}
}
/* Post increment? */
if (*end == '+'){
dec_inc = '+';
/* was: *end--; */
end--;
}
/* register in parens? */
if ((*end == ')') && (end[-1] != '\'')){
temp = end;
/* Find opening paren. */
for(--end;(*end != '(' && end != point);end--)
;
/* If I found the opening paren, get the register number. */
if (*end == '('){
tp = end + 1;
reg = tahoe_reg_parse(&tp);
if (tp != temp){
/* Not a register, but could be part of the expression. */
reg = -1;
end = temp; /* Rest the pointer back */
} else {
end--; /* Found the reg. move before opening paren. */
}
}else{
op_bad = "Couldn't find the opening '(' for the deref of this operand.";
end = point; /* Force all the rest of the tests to fail. */
}
}
/* Pre decrement? */
if (*end == '-'){
if (dec_inc != ' '){
op_bad = "Operand can't be both pre-inc and post-dec.";
end = point;
}else{
dec_inc = '-';
/* was: *end--; */
end--;
}
}
/*
* Everything between point and end is the 'expression', unless it's
* a register name.
*/
c = end[1];
end[1] = '\0';
tp = point;
imreg = tahoe_reg_parse(&point); /* Get the immediate register
if it is there.*/
if (*point != '\0'){
/* If there is junk after point, then the it's not immediate reg. */
point = tp;
imreg = -1;
}
if (imreg != -1 && reg != -1)
op_bad = "I parsed 2 registers in this operand.";
/*
* Evaluate whats left of the expression to see if it's valid.
* Note again: This assumes that the calling expression has saved
* input_line_pointer. (Nag, nag, nag!)
*/
if (*op_bad == '\0'){
/* statement has no syntax goofs yet: lets sniff the expression */
input_line_pointer = point;
expP = &(topP->exp_of_operand);
switch (expression (expP)){
/* If expression == SEG_PASS1, expression() will have set
need_pass_2 = 1. */
case SEG_ABSENT:
/* No expression. For BSD4.2 compatibility, missing expression is
absolute 0 */
expP->X_seg = SEG_ABSOLUTE;
expP->X_add_number = 0;
really_none = 1;
case SEG_ABSOLUTE:
/* for SEG_ABSOLUTE, we shouldnt need to set X_subtract_symbol,
X_add_symbol to any particular value. */
/* But, we will program defensively. Since this situation occurs
rarely so it costs us little to do so. */
expP->X_add_symbol = NULL;
expP->X_subtract_symbol = NULL;
/* How many bytes are needed to express this abs value? */
abs_width =
((((expP->X_add_number & 0xFFFFFF80) == 0) ||
((expP->X_add_number & 0xFFFFFF80) == 0xFFFFFF80)) ? 1 :
(((expP->X_add_number & 0xFFFF8000) == 0) ||
((expP->X_add_number & 0xFFFF8000) == 0xFFFF8000)) ? 2 : 4);
case SEG_TEXT:
case SEG_DATA:
case SEG_BSS:
case SEG_UNKNOWN:
break;
case SEG_DIFFERENCE:
/*
* Major bug. We can't handle the case of a
* SEG_DIFFERENCE expression in a synthetic opcode
* variable-length instruction.
* We don't have a frag type that is smart enough to
* relax a SEG_DIFFERENCE, and so we just force all
* SEG_DIFFERENCEs to behave like SEG_PASS1s.
* Clearly, if there is a demand we can invent a new or
* modified frag type and then coding up a frag for this
* case will be easy. SEG_DIFFERENCE was invented for the
* .words after a CASE opcode, and was never intended for
* instruction operands.
*/
need_pass_2 = 1;
case SEG_PASS1:
op_bad = "Can't relocate expression error.";
break;
case SEG_BIG:
/* This is an error. Tahoe doesn't allow any expressions
bigger that a 32 bit long word. Any bigger has to be referenced
by address. */
op_bad = "Expression is too large for a 32 bits.";
break;
default:
as_fatal("Complier Bug: I got segment %d in tip_op.",expP->X_seg);
break;
}
if (*input_line_pointer != '\0'){
op_bad = "Junk at end of expression.";
}
}
end[1] = c;
/* I'm done, so restore optex */
*optex = segfault;
/*
* At this point in the game, we (in theory) have all the components of
* the operand at least parsed. Now it's time to check for syntax/semantic
* errors, and build the mode.
* This is what I have:
* deferred = 1 if '*'
* call_width = 0,1,2,4
* abs_width = 0,1,2,4
* com_width = 0,1,2,4
* immediate = 1 if '$'
* ndx = -1 or reg num
* dec_inc = '-' or '+' or ' '
* reg = -1 or reg num
* imreg = -1 or reg num
* topP->exp_of_operand
* really_none
*/
/* Is there a displacement size? */
disp_size = (call_width ? call_width :
(com_width ? com_width :
abs_width ? abs_width : 0));
if (*op_bad == '\0'){
if (imreg != -1){
/* Rn */
mode = TAHOE_DIRECT_REG;
if (deferred || immediate || (dec_inc != ' ') ||
(reg != -1) || !really_none)
op_bad = "Syntax error in direct register mode.";
else if (ndx != -1)
op_bad = "You can't index a register in direct register mode.";
else if (imreg == SP_REG && access == 'r')
op_bad =
"SP can't be the source operand with direct register addressing.";
else if (access == 'a')
op_bad = "Can't take the address of a register.";
else if (access == 'b')
op_bad = "Direct Register can't be used in a branch.";
else if (width == 'q' && ((imreg % 2) || (imreg > 13)))
op_bad = "For quad access, the register must be even and < 14.";
else if (call_width)
op_bad = "You can't cast a direct register.";
if (*op_bad == '\0'){
/* No errors, check for warnings */
if (width == 'q' && imreg == 12)
as_warn("Using reg 14 for quadwords can tromp the FP register.");
reg = imreg;
}
/* We know: imm = -1 */
}else if (dec_inc == '-'){
/* -(SP) */
mode = TAHOE_AUTO_DEC;
if (deferred || immediate || !really_none)
op_bad = "Syntax error in auto-dec mode.";
else if (ndx != -1)
op_bad = "You can't have an index auto dec mode.";
else if (access == 'r')
op_bad = "Auto dec mode cant be used for reading.";
else if (reg != SP_REG)
op_bad = "Auto dec only works of the SP register.";
else if (access == 'b')
op_bad = "Auto dec can't be used in a branch.";
else if (width == 'q')
op_bad = "Auto dec won't work with quadwords.";
/* We know: imm = -1, dec_inc != '-' */
}else if (dec_inc == '+'){
if (immediate || !really_none)
op_bad = "Syntax error in one of the auto-inc modes.";
else if (deferred){
/* *(SP)+ */
mode = TAHOE_AUTO_INC_DEFERRED;
if (reg != SP_REG)
op_bad = "Auto inc deferred only works of the SP register.";
else if (ndx != -1)
op_bad = "You can't have an index auto inc deferred mode.";
else if (access == 'b')
op_bad = "Auto inc can't be used in a branch.";
}else{
/* (SP)+ */
mode = TAHOE_AUTO_INC;
if (access == 'm' || access == 'w')
op_bad = "You can't write to an auto inc register.";
else if (reg != SP_REG)
op_bad = "Auto inc only works of the SP register.";
else if (access == 'b')
op_bad = "Auto inc can't be used in a branch.";
else if (width == 'q')
op_bad = "Auto inc won't work with quadwords.";
else if (ndx != -1)
op_bad = "You can't have an index in auto inc mode.";
}
/* We know: imm = -1, dec_inc == ' ' */
}else if (reg != -1){
if ((ndx != -1) && (reg == SP_REG))
op_bad = "You can't index the sp register.";
if (deferred){
/* *<disp>(Rn) */
mode = TAHOE_REG_DISP_DEFERRED;
if (immediate)
op_bad = "Syntax error in register displaced mode.";
}else if (really_none){
/* (Rn) */
mode = TAHOE_REG_DEFERRED;
/* if reg = SP then cant be indexed */
}else{
/* <disp>(Rn) */
mode = TAHOE_REG_DISP;
}
/* We know: imm = -1, dec_inc == ' ', Reg = -1 */
}else{
if (really_none)
op_bad = "An offest is needed for this operand.";
if (deferred && immediate){
/* *$<ADDR> */
mode = TAHOE_ABSOLUTE_ADDR;
disp_size = 4;
}else if (immediate){
/* $<disp> */
mode = TAHOE_IMMEDIATE;
if (ndx != -1)
op_bad = "You can't index a register in immediate mode.";
if (access == 'a')
op_bad = "Immediate access can't be used as an address.";
/* ponder the wisdom of a cast because it doesn't do any good. */
}else if (deferred){
/* *<disp> */
mode = TAHOE_DISP_REL_DEFERRED;
}else{
/* <disp> */
mode = TAHOE_DISPLACED_RELATIVE;
}
}
}
/*
* At this point, all the errors we can do have be checked for.
* We can build the 'top'. */
topP->top_ndx = ndx;
topP->top_reg = reg;
topP->top_mode = mode;
topP->top_error = op_bad;
topP->top_dispsize = disp_size;
} /* tip_op */
/*
* t i p ( )
*
* This converts a string into a tahoe instruction.
* The string must be a bare single instruction in tahoe (with BSD4 frobs)
* format.
* It provides at most one fatal error message (which stops the scan)
* some warning messages as it finds them.
* The tahoe instruction is returned in exploded form.
*
* The exploded instruction is returned to a struct tit of your choice.
* #include "tahoe-inst.h" to know what a struct tit is.
*
*/
static void
tip (titP, instring)
struct tit *titP; /* We build an exploded instruction here. */
char *instring; /* Text of a vax instruction: we modify. */
{
register struct tot_wot *twP = NULL; /* How to bit-encode this opcode. */
register char *p; /* 1/skip whitespace.2/scan vot_how */
register char *q; /* */
register unsigned char count; /* counts number of operands seen */
register struct top *operandp;/* scan operands in struct tit */
register char *alloperr = ""; /* error over all operands */
register char c; /* Remember char, (we clobber it
with '\0' temporarily). */
char *save_input_line_pointer;
if (*instring == ' ')
++instring; /* Skip leading whitespace. */
for (p = instring; *p && *p != ' '; p++)
; /* MUST end in end-of-string or
exactly 1 space. */
/* Scanned up to end of operation-code. */
/* Operation-code is ended with whitespace. */
if (p == instring){
titP->tit_error = "No operator";
count = 0;
titP->tit_opcode = 0;
} else {
c = *p;
*p = '\0';
/*
* Here with instring pointing to what better be an op-name, and p
* pointing to character just past that.
* We trust instring points to an op-name, with no whitespace.
*/
twP = (struct tot_wot *) hash_find(op_hash, instring);
*p = c; /* Restore char after op-code. */
if (twP == 0){
titP->tit_error = "Unknown operator";
count = 0;
titP->tit_opcode = 0;
}else{
/*
* We found a match! So lets pick up as many operands as the
* instruction wants, and even gripe if there are too many.
* We expect comma to seperate each operand.
* We let instring track the text, while p tracks a part of the
* struct tot.
*/
count = 0; /* no operands seen yet */
instring = p+(*p!='\0'); /* point past the operation code */
/* tip_op() screws with the input_line_pointer, so save it before
I jump in */
save_input_line_pointer = input_line_pointer;
for (p = twP->args, operandp = titP->tit_operand;
!*alloperr && *p;
operandp++, p += 2){
/*
* Here to parse one operand. Leave instring pointing just
* past any one ',' that marks the end of this operand.
*/
if (!p[1])
as_fatal("Compiler bug: ODD number of bytes in arg structure %s.",
twP->args);
else if (*instring){
for (q = instring; (*q != ',' && *q != '\0'); q++){
if (*q == '\'' && q[1] != '\0') /* Jump quoted characters */
q++;
}
c = *q;
/*
* Q points to ',' or '\0' that ends argument. C is that
* character.
*/
*q = '\0';
operandp->top_access = p[0];
operandp->top_width = p[1];
tip_op(instring-1, operandp);
*q = c; /* Restore input text. */
if (*(operandp->top_error)){
alloperr = operandp->top_error;
}
instring = q + (c ? 1 : 0); /* next operand (if any) */
count++; /* won another argument, may have an operr */
}else
alloperr = "Not enough operands";
}
/* Restore the pointer. */
input_line_pointer = save_input_line_pointer;
if (!*alloperr){
if (*instring == ' ')
instring++; /* Skip whitespace. */
if (*instring)
alloperr = "Too many operands";
}
titP->tit_error = alloperr;
}
}
titP->tit_opcode = twP->code; /* The op-code. */
titP->tit_operands = count;
} /* tip */
/* md_assemble() emit frags for 1 instruction */
void
md_assemble (instruction_string)
char *instruction_string; /* A string: assemble 1 instruction. */
{
char *p;
register struct top *operandP; /* An operand. Scans all operands. */
/* char c_save; fixme: remove this line */ /* What used to live after an expression. */
/* struct frag *fragP; fixme: remove this line */ /* Fragment of code we just made. */
/* register struct top *end_operandP; fixme: remove this line */ /* -> slot just after last operand
Limit of the for (each operand). */
register expressionS *expP; /* -> expression values for this operand */
/* These refer to an instruction operand expression. */
segT to_seg; /* Target segment of the address. */
register valueT this_add_number;
register struct symbol *this_add_symbol; /* +ve (minuend) symbol. */
/* tahoe_opcodeT opcode_as_number; fixme: remove this line */ /* The opcode as a number. */
char *opcodeP; /* Where it is in a frag. */
/* char *opmodeP; fixme: remove this line */ /* Where opcode type is, in a frag. */
int dispsize; /* From top_dispsize: tahoe_operand_width
(in bytes) */
int is_undefined; /* 1 if operand expression's
segment not known yet. */
int pc_rel; /* Is this operand pc relative? */
/* Decode the operand. */
tip(&t, instruction_string);
/*
* Check to see if this operand decode properly.
* Notice that we haven't made any frags yet.
* If it goofed, then this instruction will wedge in any pass,
* and we can safely flush it, without causing interpass symbol phase
* errors. That is, without changing label values in different passes.
*/
if (*t.tit_error){
as_warn("Ignoring statement due to \"%s\"", t.tit_error);
}else{
/* We saw no errors in any operands - try to make frag(s) */
/* Emit op-code. */
/* Remember where it is, in case we want to modify the op-code later. */
opcodeP = frag_more(1);
*opcodeP = t.tit_opcode;
/* Now do each operand. */
for (operandP = t.tit_operand;
operandP < t.tit_operand + t.tit_operands;
operandP++){ /* for each operand */
expP = &(operandP->exp_of_operand);
if (operandP->top_ndx >= 0){
/* Indexed addressing byte
Legality of indexed mode already checked: it is OK */
FRAG_APPEND_1_CHAR(0x40 + operandP->top_ndx);
} /* if(top_ndx>=0) */
/* Here to make main operand frag(s). */
this_add_number = expP->X_add_number;
this_add_symbol = expP->X_add_symbol;
to_seg = expP->X_seg;
know (to_seg == SEG_UNKNOWN||\
to_seg == SEG_ABSOLUTE||\
to_seg == SEG_DATA||\
to_seg == SEG_TEXT||\
to_seg == SEG_BSS);
is_undefined = (to_seg == SEG_UNKNOWN);
/* Do we know how big this opperand is? */
dispsize = operandP->top_dispsize;
pc_rel = 0;
/* Deal with the branch possabilities. (Note, this doesn't include
jumps.)*/
if (operandP->top_access == 'b'){
/* Branches must be expressions. A psuedo branch can also jump to
an absolute address. */
if (to_seg == now_seg || is_undefined){
/* If is_undefined, then it might BECOME now_seg by relax time. */
if (dispsize){
/* I know how big the branch is supposed to be (it's a normal
branch), so I set up the frag, and let GAS do the rest. */
p = frag_more (dispsize);
fix_new (frag_now, p - frag_now->fr_literal, dispsize,
this_add_symbol, 0, this_add_number, 1, NO_RELOC);
} else {
/* (to_seg==now_seg || to_seg == SEG_UNKNOWN) && dispsize==0 */
/* If we don't know how big it is, then its a synthetic branch,
so we set up a simple relax state. */
switch (operandP->top_width){
case TAHOE_WIDTH_CONDITIONAL_JUMP:
/* Simple (conditional) jump. I may have to reverse the
condition of opcodeP, and then jump to my destination.
I set 1 byte aside for the branch off set, and could need 6
more bytes for the pc_rel jump */
frag_var (rs_machine_dependent, 7, 1,
ENCODE_RELAX (STATE_CONDITIONAL_BRANCH,
is_undefined ? STATE_UNDF : STATE_BYTE),
this_add_symbol, this_add_number, opcodeP);
break;
case TAHOE_WIDTH_ALWAYS_JUMP:
/* Simple (unconditional) jump. I may have to convert this to
a word branch, or an absolute jump. */
frag_var (rs_machine_dependent, 5, 1,
ENCODE_RELAX (STATE_ALWAYS_BRANCH,
is_undefined ? STATE_UNDF : STATE_BYTE),
this_add_symbol, this_add_number, opcodeP);
break;
/* The smallest size for the next 2 cases is word. */
case TAHOE_WIDTH_BIG_REV_JUMP:
frag_var (rs_machine_dependent, 8, 2,
ENCODE_RELAX (STATE_BIG_REV_BRANCH,
is_undefined ? STATE_UNDF : STATE_WORD),
this_add_symbol, this_add_number,
opcodeP);
break;
case TAHOE_WIDTH_BIG_NON_REV_JUMP:
frag_var (rs_machine_dependent, 10, 2,
ENCODE_RELAX (STATE_BIG_NON_REV_BRANCH,
is_undefined ? STATE_UNDF : STATE_WORD),
this_add_symbol, this_add_number,
opcodeP);
break;
default:
as_fatal("Compliler bug: Got a case (%d) I wasn't expecting.",
operandP->top_width);
}
}
}else{
/* to_seg != now_seg && to_seg != seg_unknown (still in branch)
In other words, I'm jumping out of my segment so extend the
branches to jumps, and let GAS fix them. */
/* These are "branches" what will always be branches around a jump
to the correct addresss in real life.
If to_seg is SEG_ABSOLUTE, just encode the branch in,
else let GAS fix the address. */
switch (operandP->top_width){
/* The theory:
For SEG_ABSOLUTE, then mode is ABSOLUTE_ADDR, jump
to that addresss (not pc_rel).
For other segs, address is a long word PC rel jump. */
case TAHOE_WIDTH_CONDITIONAL_JUMP:
/* b<cond> */
/* To reverse the condition in a TAHOE branch,
complement bit 4 */
*opcodeP ^= 0x10;
p = frag_more (7);
*p++ = 6;
*p++ = TAHOE_JMP;
*p++ = (operandP->top_mode ==
TAHOE_ABSOLUTE_ADDR ? TAHOE_ABSOLUTE_ADDR :
TAHOE_PC_REL_LONG);
fix_new (frag_now, p - frag_now->fr_literal, 4,
this_add_symbol, 0, this_add_number,
(to_seg != SEG_ABSOLUTE), NO_RELOC);
/*
* Now (eg) BLEQ 1f
* JMP foo
* 1:
*/
break;
case TAHOE_WIDTH_ALWAYS_JUMP:
/* br, just turn it into a jump */
*opcodeP = TAHOE_JMP;
p = frag_more (5);
*p++ = (operandP->top_mode ==
TAHOE_ABSOLUTE_ADDR ? TAHOE_ABSOLUTE_ADDR :
TAHOE_PC_REL_LONG);
fix_new (frag_now, p - frag_now->fr_literal, 4,
this_add_symbol, 0, this_add_number,
(to_seg != SEG_ABSOLUTE), NO_RELOC);
/* Now (eg) JMP foo */
break;
case TAHOE_WIDTH_BIG_REV_JUMP:
p = frag_more (8);
*opcodeP ^= 0x10;
*p++ = 0;
*p++ = 6;
*p++ = TAHOE_JMP;
*p++ = (operandP->top_mode ==
TAHOE_ABSOLUTE_ADDR ? TAHOE_ABSOLUTE_ADDR :
TAHOE_PC_REL_LONG);
fix_new (frag_now, p - frag_now->fr_literal, 4,
this_add_symbol, 0, this_add_number,
(to_seg != SEG_ABSOLUTE), NO_RELOC);
/*
* Now (eg) ACBx 1f
* JMP foo
* 1:
*/
break;
case TAHOE_WIDTH_BIG_NON_REV_JUMP:
p = frag_more (10);
*p++ = 0;
*p++ = 2;
*p++ = TAHOE_BRB;
*p++ = 6;
*p++ = TAHOE_JMP;
*p++ = (operandP->top_mode ==
TAHOE_ABSOLUTE_ADDR ? TAHOE_ABSOLUTE_ADDR :
TAHOE_PC_REL_LONG);
fix_new (frag_now, p - frag_now->fr_literal, 4,
this_add_symbol, 0, this_add_number,
(to_seg != SEG_ABSOLUTE), NO_RELOC);
/*
* Now (eg) xOBxxx 1f
* BRB 2f
* 1: JMP @#foo
* 2:
*/
break;
case 'b':
case 'w':
as_warn("Real branch displacements must be expressions.");
break;
default:
as_fatal("Complier error: I got an unknown synthetic branch :%c",
operandP->top_width);
break;
}
}
}else{
/* It ain't a branch operand. */
switch (operandP->top_mode){
/* Auto-foo access, only works for one reg (SP)
so the only thing needed is the mode. */
case TAHOE_AUTO_DEC:
case TAHOE_AUTO_INC:
case TAHOE_AUTO_INC_DEFERRED:
FRAG_APPEND_1_CHAR(operandP->top_mode);
break;
/* Numbered Register only access. Only thing needed is the
mode + Register number */
case TAHOE_DIRECT_REG:
case TAHOE_REG_DEFERRED:
FRAG_APPEND_1_CHAR(operandP->top_mode + operandP->top_reg);
break;
/* An absolute address. It's size is always 5 bytes.
(mode_type + 4 byte address). */
case TAHOE_ABSOLUTE_ADDR:
know((this_add_symbol == NULL));
p = frag_more(5);
*p = TAHOE_ABSOLUTE_ADDR;
md_number_to_chars(p+1,this_add_number,4);
break;
/* Immediate data. If the size isn't known, then it's an address
+ and offset, which is 4 bytes big. */
case TAHOE_IMMEDIATE:
if (this_add_symbol != NULL){
p = frag_more (5);
*p++ = TAHOE_IMMEDIATE_LONGWORD;
fix_new (frag_now, p - frag_now->fr_literal,
4, this_add_symbol,0,this_add_number,
0, NO_RELOC);
}else{
/* It's a integer, and I know it's size. */
if ((unsigned) this_add_number < 0x40){
/* Will it fit in a literal? */
FRAG_APPEND_1_CHAR((byte) this_add_number);
}else{
p = frag_more(dispsize+1);
switch(dispsize){
case 1:
*p++ = TAHOE_IMMEDIATE_BYTE;
*p = (byte) this_add_number;
break;
case 2:
*p++ = TAHOE_IMMEDIATE_WORD;
md_number_to_chars(p,this_add_number,2);
break;
case 4:
*p++ = TAHOE_IMMEDIATE_LONGWORD;
md_number_to_chars(p,this_add_number,4);
break;
}
}
}
break;
/* Distance from the PC. If the size isn't known, we have to relax
into it. The difference between this and disp(sp) is that
this offset is pc_rel, and disp(sp) isn't.
Note the drop through code. */
case TAHOE_DISPLACED_RELATIVE:
case TAHOE_DISP_REL_DEFERRED:
operandP->top_reg = PC_REG;
pc_rel = 1;
/* Register, plus a displacement mode. Save the register number,
and weather its deffered or not, and relax the size if it isn't
known. */
case TAHOE_REG_DISP:
case TAHOE_REG_DISP_DEFERRED:
if (operandP->top_mode == TAHOE_DISP_REL_DEFERRED ||
operandP->top_mode == TAHOE_REG_DISP_DEFERRED)
operandP->top_reg += 0x10; /* deffered mode is always 0x10 higher
than it's non-deffered sibling. */
/* Is this a value out of this segment?
The first part of this conditional is a cludge to make gas
produce the same output as 'as' when there is a lable, in
the current segment, displaceing a register. It's strange,
and no one in their right mind would do it, but it's easy
to cludge. */
if ((dispsize == 0 && !pc_rel) ||
(to_seg != now_seg && !is_undefined && to_seg != SEG_ABSOLUTE))
dispsize = 4;
if (dispsize == 0){
/*
* We have a SEG_UNKNOWN symbol, or the size isn't cast.
* It might turn out to be in the same segment as
* the instruction, permitting relaxation.
*/
p = frag_var(rs_machine_dependent, 5, 2,
ENCODE_RELAX(STATE_PC_RELATIVE,
is_undefined ? STATE_UNDF:STATE_BYTE),
this_add_symbol, this_add_number,0);
*p = operandP->top_reg;
}else{
/* Either this is an abs, or a cast. */
p = frag_more (dispsize + 1);
switch(dispsize){
case 1:
*p = TAHOE_PC_OR_BYTE + operandP->top_reg;
break;
case 2:
*p = TAHOE_PC_OR_WORD + operandP->top_reg;
break;
case 4:
*p = TAHOE_PC_OR_LONG + operandP->top_reg;
break;
};
fix_new (frag_now, p + 1 - frag_now->fr_literal,
dispsize, this_add_symbol,0,this_add_number,
pc_rel, NO_RELOC);
}
break;
default:
as_fatal("Barf, bad mode %x\n",operandP->top_mode);
}
}
} /* for(operandP) */
} /* if(!need_pass_2 && !goofed) */
} /* tahoe_assemble() */
/* We have no need to default values of symbols. */
/* ARGSUSED */
symbolS *md_undefined_symbol(name)
char *name;
{
return 0;
} /* md_undefined_symbol() */
/* Parse an operand that is machine-specific.
We just return without modifying the expression if we have nothing
to do. */
/* ARGSUSED */
void md_operand(expressionP)
expressionS *expressionP;
{
} /* md_operand() */
/* Round up a section size to the appropriate boundary. */
long md_section_align(segment, size)
segT segment;
long size;
{
return((size + 7) & ~7); /* Round all sects to multiple of 8 */
} /* md_section_align() */
/* Exactly what point is a PC-relative offset relative TO?
On the sparc, they're relative to the address of the offset, plus
its size. This gets us to the following instruction.
(??? Is this right? FIXME-SOON) */
long md_pcrel_from(fixP)
fixS *fixP;
{
return(fixP->fx_size + fixP->fx_where + fixP->fx_frag->fr_address);
} /* md_pcrel_from() */
/* end of tc-tahoe.c */
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