9081eec1fb
have successfully built, booted, and run a number of different ELF kernel configurations, including GENERIC. LINT also builds and links cleanly, though I have not tried to boot it. The impact on developers is virtually nil, except for two things. All linker sets that might possibly be present in the kernel must be listed in "sys/i386/i386/setdefs.h". And all C symbols that are also referenced from assembly language code must be listed in "sys/i386/include/asnames.h". It so happens that failure to do these things will have no impact on the a.out kernel. But it will break the build of the ELF kernel. The ELF bootloader works, but it is not ready to commit quite yet.
360 lines
8.3 KiB
ArmAsm
360 lines
8.3 KiB
ArmAsm
.file "reg_u_sub.S"
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/*
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* reg_u_sub.S
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*
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* Core floating point subtraction routine.
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*
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* Call from C as:
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* void reg_u_sub(FPU_REG *arg1, FPU_REG *arg2, FPU_REG *answ,
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* int control_w)
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*
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*
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* Copyright (C) 1992,1993,1994
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* W. Metzenthen, 22 Parker St, Ormond, Vic 3163,
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* Australia. E-mail billm@vaxc.cc.monash.edu.au
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* All rights reserved.
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*
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* This copyright notice covers the redistribution and use of the
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* FPU emulator developed by W. Metzenthen. It covers only its use
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* in the 386BSD, FreeBSD and NetBSD operating systems. Any other
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* use is not permitted under this copyright.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must include information specifying
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* that source code for the emulator is freely available and include
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* either:
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* a) an offer to provide the source code for a nominal distribution
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* fee, or
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* b) list at least two alternative methods whereby the source
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* can be obtained, e.g. a publically accessible bulletin board
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* and an anonymous ftp site from which the software can be
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* downloaded.
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* 3. All advertising materials specifically mentioning features or use of
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* this emulator must acknowledge that it was developed by W. Metzenthen.
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* 4. The name of W. Metzenthen may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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* W. METZENTHEN BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*
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* The purpose of this copyright, based upon the Berkeley copyright, is to
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* ensure that the covered software remains freely available to everyone.
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*
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* The software (with necessary differences) is also available, but under
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* the terms of the GNU copyleft, for the Linux operating system and for
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* the djgpp ms-dos extender.
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*
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* W. Metzenthen June 1994.
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*
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*
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* $Id: reg_u_sub.s,v 1.6 1997/02/22 09:29:27 peter Exp $
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*
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*/
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/*
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| Kernel subtraction routine reg_u_sub(reg *arg1, reg *arg2, reg *answ).
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| Takes two valid reg f.p. numbers (TW_Valid), which are
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| treated as unsigned numbers,
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| and returns their difference as a TW_Valid or TW_Zero f.p.
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| number.
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| The first number (arg1) must be the larger.
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| The returned number is normalized.
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| Basic checks are performed if PARANOID is defined.
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*/
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#include <gnu/i386/fpemul/exception.h>
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#include <gnu/i386/fpemul/fpu_asm.h>
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#include <gnu/i386/fpemul/control_w.h>
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.text
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ENTRY(reg_u_sub)
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pushl %ebp
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movl %esp,%ebp
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pushl %esi
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pushl %edi
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pushl %ebx
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movl PARAM1,%esi /* source 1 */
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movl PARAM2,%edi /* source 2 */
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#ifdef DENORM_OPERAND
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cmpl EXP_UNDER,EXP(%esi)
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jg xOp1_not_denorm
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call _denormal_operand
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orl %eax,%eax
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jnz FPU_Arith_exit
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xOp1_not_denorm:
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cmpl EXP_UNDER,EXP(%edi)
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jg xOp2_not_denorm
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call _denormal_operand
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orl %eax,%eax
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jnz FPU_Arith_exit
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xOp2_not_denorm:
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#endif DENORM_OPERAND
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/* xorl %ecx,%ecx */
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movl EXP(%esi),%ecx
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subl EXP(%edi),%ecx /* exp1 - exp2 */
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#ifdef PARANOID
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/* source 2 is always smaller than source 1 */
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/* jc L_bugged */
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js L_bugged_1
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testl $0x80000000,SIGH(%edi) /* The args are assumed to be be normalized */
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je L_bugged_2
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testl $0x80000000,SIGH(%esi)
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je L_bugged_2
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#endif PARANOID
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/*--------------------------------------+
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| Form a register holding the |
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| smaller number |
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+--------------------------------------*/
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movl SIGH(%edi),%eax /* register ms word */
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movl SIGL(%edi),%ebx /* register ls word */
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movl PARAM3,%edi /* destination */
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movl EXP(%esi),%edx
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movl %edx,EXP(%edi) /* Copy exponent to destination */
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movb SIGN(%esi),%dl
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movb %dl,SIGN(%edi) /* Copy the sign from the first arg */
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xorl %edx,%edx /* register extension */
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/*--------------------------------------+
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| Shift the temporary register |
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| right the required number of |
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| places. |
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+--------------------------------------*/
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L_shift_r:
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cmpl $32,%ecx /* shrd only works for 0..31 bits */
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jnc L_more_than_31
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/* less than 32 bits */
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shrd %cl,%ebx,%edx
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shrd %cl,%eax,%ebx
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shr %cl,%eax
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jmp L_shift_done
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L_more_than_31:
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cmpl $64,%ecx
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jnc L_more_than_63
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subb $32,%cl
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jz L_exactly_32
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shrd %cl,%eax,%edx
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shr %cl,%eax
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orl %ebx,%ebx
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jz L_more_31_no_low /* none of the lowest bits is set */
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orl $1,%edx /* record the fact in the extension */
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L_more_31_no_low:
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movl %eax,%ebx
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xorl %eax,%eax
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jmp L_shift_done
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L_exactly_32:
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movl %ebx,%edx
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movl %eax,%ebx
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xorl %eax,%eax
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jmp L_shift_done
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L_more_than_63:
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cmpw $65,%cx
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jnc L_more_than_64
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/* Shift right by 64 bits */
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movl %eax,%edx
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orl %ebx,%ebx
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jz L_more_63_no_low
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orl $1,%edx
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jmp L_more_63_no_low
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L_more_than_64:
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jne L_more_than_65
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/* Shift right by 65 bits */
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/* Carry is clear if we get here */
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movl %eax,%edx
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rcrl %edx
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jnc L_shift_65_nc
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orl $1,%edx
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jmp L_more_63_no_low
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L_shift_65_nc:
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orl %ebx,%ebx
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jz L_more_63_no_low
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orl $1,%edx
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jmp L_more_63_no_low
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L_more_than_65:
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movl $1,%edx /* The shifted nr always at least one '1' */
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L_more_63_no_low:
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xorl %ebx,%ebx
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xorl %eax,%eax
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L_shift_done:
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L_subtr:
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/*------------------------------+
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| Do the subtraction |
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+------------------------------*/
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xorl %ecx,%ecx
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subl %edx,%ecx
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movl %ecx,%edx
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movl SIGL(%esi),%ecx
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sbbl %ebx,%ecx
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movl %ecx,%ebx
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movl SIGH(%esi),%ecx
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sbbl %eax,%ecx
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movl %ecx,%eax
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#ifdef PARANOID
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/* We can never get a borrow */
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jc L_bugged
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#endif PARANOID
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/*--------------------------------------+
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| Normalize the result |
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+--------------------------------------*/
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testl $0x80000000,%eax
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jnz L_round /* no shifting needed */
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orl %eax,%eax
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jnz L_shift_1 /* shift left 1 - 31 bits */
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orl %ebx,%ebx
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jnz L_shift_32 /* shift left 32 - 63 bits */
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/* A rare case, the only one which is non-zero if we got here
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// is: 1000000 .... 0000
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// -0111111 .... 1111 1
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// --------------------
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// 0000000 .... 0000 1 */
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cmpl $0x80000000,%edx
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jnz L_must_be_zero
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/* Shift left 64 bits */
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subl $64,EXP(%edi)
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movl %edx,%eax
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jmp L_store
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L_must_be_zero:
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#ifdef PARANOID
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orl %edx,%edx
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jnz L_bugged_3
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#endif PARANOID
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/* The result is zero */
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movb TW_Zero,TAG(%edi)
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movl $0,EXP(%edi) /* exponent */
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movl $0,SIGL(%edi)
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movl $0,SIGH(%edi)
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jmp L_exit /* Does not underflow */
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L_shift_32:
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movl %ebx,%eax
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movl %edx,%ebx
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movl $0,%edx
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subl $32,EXP(%edi) /* Can get underflow here */
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/* We need to shift left by 1 - 31 bits */
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L_shift_1:
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bsrl %eax,%ecx /* get the required shift in %ecx */
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subl $31,%ecx
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negl %ecx
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shld %cl,%ebx,%eax
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shld %cl,%edx,%ebx
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shl %cl,%edx
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subl %ecx,EXP(%edi) /* Can get underflow here */
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L_round:
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jmp FPU_round /* Round the result */
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#ifdef PARANOID
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L_bugged_1:
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pushl EX_INTERNAL|0x206
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call EXCEPTION
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pop %ebx
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jmp L_exit
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L_bugged_2:
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pushl EX_INTERNAL|0x209
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call EXCEPTION
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pop %ebx
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jmp L_exit
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L_bugged_3:
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pushl EX_INTERNAL|0x210
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call EXCEPTION
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pop %ebx
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jmp L_exit
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L_bugged_4:
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pushl EX_INTERNAL|0x211
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call EXCEPTION
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pop %ebx
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jmp L_exit
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L_bugged:
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pushl EX_INTERNAL|0x212
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call EXCEPTION
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pop %ebx
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jmp L_exit
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#endif PARANOID
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L_store:
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/*------------------------------+
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| Store the result |
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+------------------------------*/
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movl %eax,SIGH(%edi)
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movl %ebx,SIGL(%edi)
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movb TW_Valid,TAG(%edi) /* Set the tags to TW_Valid */
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cmpl EXP_UNDER,EXP(%edi)
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jle L_underflow
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L_exit:
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popl %ebx
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popl %edi
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popl %esi
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leave
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ret
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L_underflow:
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push %edi
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call _arith_underflow
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pop %ebx
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jmp L_exit
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