166 lines
5.4 KiB
C
166 lines
5.4 KiB
C
/* Definitions for Bytecode Interpreter.
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Copyright (C) 1993, 1994 Free Software Foundation, Inc.
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU CC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
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#define MAXLITERALS 5
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struct arityvec
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{
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char ninputs;
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char noutputs;
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char nliterals;
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char literals[MAXLITERALS];
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};
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struct argtype
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{
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int modealign; /* Argument mode:alignment */
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int size; /* Argument size, in bytes */
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};
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struct callinfo
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{
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int nargs; /* Number of arguments in call */
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struct argtype retvaltype; /* Type of return value */
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struct argtype argtypes[1]; /* Argument types */
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};
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/* Structure describing a bytecode function. If this changes, we also
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need to change expand_function_end () in bc-trans.c */
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struct bytecode
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{
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int stacksize; /* Depth required of evaluation stack. */
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int localsize; /* Size in bytes of local variables. */
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unsigned char *pc0; /* Initial program counter. */
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void **ptrlit; /* Vector of (relocatable) pointer literals. */
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struct callinfo *callinfo; /* Vector of procedure call type info. */
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};
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#define INTERP_BPC 8 /* Bits per char */
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#define INTERP_BPI \
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(sizeof (int) * INTERP_BPC) /* Bits per int */
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#ifndef min
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#define min(L, R) ((L) < (R) ? (L) : (R))
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#endif
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/* bit field operations. */
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/* Low (high) mask: int with low (high) N bits set */
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#define LM(N) ((1 << (N)) - 1)
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#define HM(N) ((~LM (INTERP_BPI - (N))))
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/* Sign-extend SIZE low bits of VALUE to integer (typeof VALUE)
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Signed bitfields are loaded from memory by the sxloadBI instruction,
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which first retrieves the bitfield with XFIELD and then sign extends
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it to an SItype. */
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#define EXTEND(SIZE, VALUE) \
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({ SUtype value = (SUtype) (VALUE); \
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(value & (1 << ((SIZE) - 1)) ? value | ~LM (SIZE) : value); })
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/* Given OFFSET:SIZE for a bitfield, calculate:
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[1] BYTE_OFFSET = the byte offset of the bit field.
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[2] BIT_OFFSET = the bit offset of the bit field (less than INTERP_BPC).
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[3] NBYTES = the number of integral bytes in the bit field.
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[4] TRAILING_BITS= the number of trailing bits (less than INTERP_BPC).
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, , , , , (memory bytes)
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---------------- (bitfield)
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| | || | | (divisions)
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^ ^ ^ ^
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| | | |__ [4] (bits)
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| | |_________ [3] (bytes)
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| |_________________ [2] (bits)
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|___________________________ [1] (bytes)
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The above applies to BYTE_LOW_ENDIAN machines. In BYTE_BIG_ENDIAN machines, the
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bit numbering is reversed (i.e. bit 0 is the sign bit).
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(Alright, so I drew this to keep my tongue in cheek while writing the code below,
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not because I'm into ASCII art.) */
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#define BI_PARAMS(OFFSET, SIZE, BYTE_OFFSET, BIT_OFFSET, NBYTES, TRAILING_BITS) \
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{ BYTE_OFFSET = (OFFSET) / (INTERP_BPC); \
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BIT_OFFSET = (OFFSET) % (INTERP_BPC); \
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NBYTES = ((SIZE) - (INTERP_BPC - (BIT_OFFSET))) / INTERP_BPC; \
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if ((NBYTES) < 0 || ((NBYTES) > 64)) \
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NBYTES = 0; \
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if ((SIZE) + (BIT_OFFSET) <= INTERP_BPC) \
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TRAILING_BITS = 0; \
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else \
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TRAILING_BITS = ((SIZE) - (INTERP_BPC - (BIT_OFFSET))) % INTERP_BPC; }
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/* SHIFT_IN_BITS retrieves NBITS bits from SOURCE and shifts into
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DEST. The bit field starts OFFSET bits into SOURCE.
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OR_IN_BITS copies the NBITS low bits from VALUE into a the bitfield in
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DEST offset by OFFSET bits. */
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#if BYTES_BIG_ENDIAN
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#define SHIFT_IN_BITS(DEST, SOURCE, OFFSET, NBITS) \
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(DEST = ((DEST) << (NBITS)) \
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| (LM ((NBITS)) \
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& ((SOURCE) >> (INTERP_BPC - (OFFSET) - (NBITS)))))
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#define OR_IN_BITS(DEST, VALUE, OFFSET, NBITS) \
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(DEST = ((DEST) & ~(LM ((NBITS)) << (INTERP_BPC - (OFFSET) - (NBITS)))) \
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| (((VALUE) & LM ((NBITS))) << (INTERP_BPC - (OFFSET) - (NBITS))))
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#else
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#define SHIFT_IN_BITS(DEST, SOURCE, OFFSET, NBITS) \
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(DEST = ((DEST) << (NBITS)) \
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| (LM ((NBITS)) \
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& ((SOURCE) >> (OFFSET))))
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#define OR_IN_BITS(DEST, VALUE, OFFSET, NBITS) \
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(DEST = ((DEST) & ~(LM ((NBITS)) << (OFFSET))) \
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| (((VALUE) & LM ((NBITS))) << (OFFSET)))
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#endif
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/* Procedure call; arguments are a pointer to the function to be called,
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a pointer to a place to store the return value, a pointer to a vector
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describing the type of procedure call, and the interpreter's stack pointer,
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which will point to the first of the arguments at this point. */
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#define CALL(FUNC, CALLDESC, RETVAL, SP) __call(FUNC, CALLDESC, RETVAL, SP)
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/* Procedure return; arguments are a pointer to the calldesc for this
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function, and a pointer to the place where the value to be returned
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may be found. Generally the MACHARGS above contain a machine dependent
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cookie that is used to determine where to jump to. */
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#define PROCRET(CALLDESC, RETVAL) return
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