mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-30 12:04:07 +00:00
358 lines
8.2 KiB
ArmAsm
358 lines
8.2 KiB
ArmAsm
.file "reg_u_sub.S"
|
|
/*
|
|
* reg_u_sub.S
|
|
*
|
|
* Core floating point subtraction routine.
|
|
*
|
|
* Call from C as:
|
|
* void reg_u_sub(FPU_REG *arg1, FPU_REG *arg2, FPU_REG *answ,
|
|
* int control_w)
|
|
*
|
|
*
|
|
* Copyright (C) 1992,1993,1994
|
|
* W. Metzenthen, 22 Parker St, Ormond, Vic 3163,
|
|
* Australia. E-mail billm@vaxc.cc.monash.edu.au
|
|
* All rights reserved.
|
|
*
|
|
* This copyright notice covers the redistribution and use of the
|
|
* FPU emulator developed by W. Metzenthen. It covers only its use
|
|
* in the 386BSD, FreeBSD and NetBSD operating systems. Any other
|
|
* use is not permitted under this copyright.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must include information specifying
|
|
* that source code for the emulator is freely available and include
|
|
* either:
|
|
* a) an offer to provide the source code for a nominal distribution
|
|
* fee, or
|
|
* b) list at least two alternative methods whereby the source
|
|
* can be obtained, e.g. a publically accessible bulletin board
|
|
* and an anonymous ftp site from which the software can be
|
|
* downloaded.
|
|
* 3. All advertising materials specifically mentioning features or use of
|
|
* this emulator must acknowledge that it was developed by W. Metzenthen.
|
|
* 4. The name of W. Metzenthen may not be used to endorse or promote
|
|
* products derived from this software without specific prior written
|
|
* permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
|
|
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
|
|
* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
|
|
* W. METZENTHEN BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
|
|
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
|
|
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
|
|
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
|
|
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
|
|
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
|
|
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
*
|
|
* The purpose of this copyright, based upon the Berkeley copyright, is to
|
|
* ensure that the covered software remains freely available to everyone.
|
|
*
|
|
* The software (with necessary differences) is also available, but under
|
|
* the terms of the GNU copyleft, for the Linux operating system and for
|
|
* the djgpp ms-dos extender.
|
|
*
|
|
* W. Metzenthen June 1994.
|
|
*
|
|
*
|
|
* $FreeBSD$
|
|
*
|
|
*/
|
|
|
|
/*
|
|
| Kernel subtraction routine reg_u_sub(reg *arg1, reg *arg2, reg *answ).
|
|
| Takes two valid reg f.p. numbers (TW_Valid), which are
|
|
| treated as unsigned numbers,
|
|
| and returns their difference as a TW_Valid or TW_Zero f.p.
|
|
| number.
|
|
| The first number (arg1) must be the larger.
|
|
| The returned number is normalized.
|
|
| Basic checks are performed if PARANOID is defined.
|
|
*/
|
|
|
|
#include <gnu/i386/fpemul/fpu_asm.h>
|
|
|
|
.text
|
|
ENTRY(reg_u_sub)
|
|
pushl %ebp
|
|
movl %esp,%ebp
|
|
pushl %esi
|
|
pushl %edi
|
|
pushl %ebx
|
|
|
|
movl PARAM1,%esi /* source 1 */
|
|
movl PARAM2,%edi /* source 2 */
|
|
|
|
#ifdef DENORM_OPERAND
|
|
cmpl EXP_UNDER,EXP(%esi)
|
|
jg xOp1_not_denorm
|
|
|
|
call denormal_operand
|
|
orl %eax,%eax
|
|
jnz FPU_Arith_exit
|
|
|
|
xOp1_not_denorm:
|
|
cmpl EXP_UNDER,EXP(%edi)
|
|
jg xOp2_not_denorm
|
|
|
|
call denormal_operand
|
|
orl %eax,%eax
|
|
jnz FPU_Arith_exit
|
|
|
|
xOp2_not_denorm:
|
|
#endif /* DENORM_OPERAND */
|
|
|
|
/* xorl %ecx,%ecx */
|
|
movl EXP(%esi),%ecx
|
|
subl EXP(%edi),%ecx /* exp1 - exp2 */
|
|
|
|
#ifdef PARANOID
|
|
/* source 2 is always smaller than source 1 */
|
|
/* jc L_bugged */
|
|
js L_bugged_1
|
|
|
|
testl $0x80000000,SIGH(%edi) /* The args are assumed to be be normalized */
|
|
je L_bugged_2
|
|
|
|
testl $0x80000000,SIGH(%esi)
|
|
je L_bugged_2
|
|
#endif /* PARANOID */
|
|
|
|
/*--------------------------------------+
|
|
| Form a register holding the |
|
|
| smaller number |
|
|
+--------------------------------------*/
|
|
movl SIGH(%edi),%eax /* register ms word */
|
|
movl SIGL(%edi),%ebx /* register ls word */
|
|
|
|
movl PARAM3,%edi /* destination */
|
|
movl EXP(%esi),%edx
|
|
movl %edx,EXP(%edi) /* Copy exponent to destination */
|
|
movb SIGN(%esi),%dl
|
|
movb %dl,SIGN(%edi) /* Copy the sign from the first arg */
|
|
|
|
xorl %edx,%edx /* register extension */
|
|
|
|
/*--------------------------------------+
|
|
| Shift the temporary register |
|
|
| right the required number of |
|
|
| places. |
|
|
+--------------------------------------*/
|
|
L_shift_r:
|
|
cmpl $32,%ecx /* shrd only works for 0..31 bits */
|
|
jnc L_more_than_31
|
|
|
|
/* less than 32 bits */
|
|
shrd %cl,%ebx,%edx
|
|
shrd %cl,%eax,%ebx
|
|
shr %cl,%eax
|
|
jmp L_shift_done
|
|
|
|
L_more_than_31:
|
|
cmpl $64,%ecx
|
|
jnc L_more_than_63
|
|
|
|
subb $32,%cl
|
|
jz L_exactly_32
|
|
|
|
shrd %cl,%eax,%edx
|
|
shr %cl,%eax
|
|
orl %ebx,%ebx
|
|
jz L_more_31_no_low /* none of the lowest bits is set */
|
|
|
|
orl $1,%edx /* record the fact in the extension */
|
|
|
|
L_more_31_no_low:
|
|
movl %eax,%ebx
|
|
xorl %eax,%eax
|
|
jmp L_shift_done
|
|
|
|
L_exactly_32:
|
|
movl %ebx,%edx
|
|
movl %eax,%ebx
|
|
xorl %eax,%eax
|
|
jmp L_shift_done
|
|
|
|
L_more_than_63:
|
|
cmpw $65,%cx
|
|
jnc L_more_than_64
|
|
|
|
/* Shift right by 64 bits */
|
|
movl %eax,%edx
|
|
orl %ebx,%ebx
|
|
jz L_more_63_no_low
|
|
|
|
orl $1,%edx
|
|
jmp L_more_63_no_low
|
|
|
|
L_more_than_64:
|
|
jne L_more_than_65
|
|
|
|
/* Shift right by 65 bits */
|
|
/* Carry is clear if we get here */
|
|
movl %eax,%edx
|
|
rcrl %edx
|
|
jnc L_shift_65_nc
|
|
|
|
orl $1,%edx
|
|
jmp L_more_63_no_low
|
|
|
|
L_shift_65_nc:
|
|
orl %ebx,%ebx
|
|
jz L_more_63_no_low
|
|
|
|
orl $1,%edx
|
|
jmp L_more_63_no_low
|
|
|
|
L_more_than_65:
|
|
movl $1,%edx /* The shifted nr always at least one '1' */
|
|
|
|
L_more_63_no_low:
|
|
xorl %ebx,%ebx
|
|
xorl %eax,%eax
|
|
|
|
L_shift_done:
|
|
L_subtr:
|
|
/*------------------------------+
|
|
| Do the subtraction |
|
|
+------------------------------*/
|
|
xorl %ecx,%ecx
|
|
subl %edx,%ecx
|
|
movl %ecx,%edx
|
|
movl SIGL(%esi),%ecx
|
|
sbbl %ebx,%ecx
|
|
movl %ecx,%ebx
|
|
movl SIGH(%esi),%ecx
|
|
sbbl %eax,%ecx
|
|
movl %ecx,%eax
|
|
|
|
#ifdef PARANOID
|
|
/* We can never get a borrow */
|
|
jc L_bugged
|
|
#endif /* PARANOID */
|
|
|
|
/*--------------------------------------+
|
|
| Normalize the result |
|
|
+--------------------------------------*/
|
|
testl $0x80000000,%eax
|
|
jnz L_round /* no shifting needed */
|
|
|
|
orl %eax,%eax
|
|
jnz L_shift_1 /* shift left 1 - 31 bits */
|
|
|
|
orl %ebx,%ebx
|
|
jnz L_shift_32 /* shift left 32 - 63 bits */
|
|
|
|
/* A rare case, the only one which is non-zero if we got here
|
|
// is: 1000000 .... 0000
|
|
// -0111111 .... 1111 1
|
|
// --------------------
|
|
// 0000000 .... 0000 1 */
|
|
|
|
cmpl $0x80000000,%edx
|
|
jnz L_must_be_zero
|
|
|
|
/* Shift left 64 bits */
|
|
subl $64,EXP(%edi)
|
|
movl %edx,%eax
|
|
jmp L_store
|
|
|
|
L_must_be_zero:
|
|
#ifdef PARANOID
|
|
orl %edx,%edx
|
|
jnz L_bugged_3
|
|
#endif /* PARANOID */
|
|
|
|
/* The result is zero */
|
|
movb TW_Zero,TAG(%edi)
|
|
movl $0,EXP(%edi) /* exponent */
|
|
movl $0,SIGL(%edi)
|
|
movl $0,SIGH(%edi)
|
|
jmp L_exit /* Does not underflow */
|
|
|
|
L_shift_32:
|
|
movl %ebx,%eax
|
|
movl %edx,%ebx
|
|
movl $0,%edx
|
|
subl $32,EXP(%edi) /* Can get underflow here */
|
|
|
|
/* We need to shift left by 1 - 31 bits */
|
|
L_shift_1:
|
|
bsrl %eax,%ecx /* get the required shift in %ecx */
|
|
subl $31,%ecx
|
|
negl %ecx
|
|
shld %cl,%ebx,%eax
|
|
shld %cl,%edx,%ebx
|
|
shl %cl,%edx
|
|
subl %ecx,EXP(%edi) /* Can get underflow here */
|
|
|
|
L_round:
|
|
jmp FPU_round /* Round the result */
|
|
|
|
|
|
#ifdef PARANOID
|
|
L_bugged_1:
|
|
pushl EX_INTERNAL|0x206
|
|
call EXCEPTION
|
|
pop %ebx
|
|
jmp L_exit
|
|
|
|
L_bugged_2:
|
|
pushl EX_INTERNAL|0x209
|
|
call EXCEPTION
|
|
pop %ebx
|
|
jmp L_exit
|
|
|
|
L_bugged_3:
|
|
pushl EX_INTERNAL|0x210
|
|
call EXCEPTION
|
|
pop %ebx
|
|
jmp L_exit
|
|
|
|
L_bugged_4:
|
|
pushl EX_INTERNAL|0x211
|
|
call EXCEPTION
|
|
pop %ebx
|
|
jmp L_exit
|
|
|
|
L_bugged:
|
|
pushl EX_INTERNAL|0x212
|
|
call EXCEPTION
|
|
pop %ebx
|
|
jmp L_exit
|
|
#endif /* PARANOID */
|
|
|
|
|
|
L_store:
|
|
/*------------------------------+
|
|
| Store the result |
|
|
+------------------------------*/
|
|
movl %eax,SIGH(%edi)
|
|
movl %ebx,SIGL(%edi)
|
|
|
|
movb TW_Valid,TAG(%edi) /* Set the tags to TW_Valid */
|
|
|
|
cmpl EXP_UNDER,EXP(%edi)
|
|
jle L_underflow
|
|
|
|
L_exit:
|
|
popl %ebx
|
|
popl %edi
|
|
popl %esi
|
|
leave
|
|
ret
|
|
|
|
|
|
L_underflow:
|
|
push %edi
|
|
call arith_underflow
|
|
pop %ebx
|
|
jmp L_exit
|
|
|