round_Xsig.S
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/*---------------------------------------------------------------------------+
| round_Xsig.S |
| |
| Copyright (C) 1992,1993,1994,1995 |
| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
| Australia. E-mail billm@jacobi.maths.monash.edu.au |
| |
| Normalize and round a 12 byte quantity. |
| Call from C as: |
| int round_Xsig(Xsig *n) |
| |
| Normalize a 12 byte quantity. |
| Call from C as: |
| int norm_Xsig(Xsig *n) |
| |
| Each function returns the size of the shift (nr of bits). |
| |
+---------------------------------------------------------------------------*/
.file "round_Xsig.S"
#include "fpu_emu.h"
.text
ENTRY(round_Xsig)
pushl %ebp
movl %esp,%ebp
pushl %ebx /* Reserve some space */
pushl %ebx
pushl %esi
movl PARAM1,%esi
movl 8(%esi),%edx
movl 4(%esi),%ebx
movl (%esi),%eax
movl $0,-4(%ebp)
orl %edx,%edx /* ms bits */
js L_round /* Already normalized */
jnz L_shift_1 /* Shift left 1 - 31 bits */
movl %ebx,%edx
movl %eax,%ebx
xorl %eax,%eax
movl $-32,-4(%ebp)
/* We need to shift left by 1 - 31 bits */
L_shift_1:
bsrl %edx,%ecx /* get the required shift in %ecx */
subl $31,%ecx
negl %ecx
subl %ecx,-4(%ebp)
shld %cl,%ebx,%edx
shld %cl,%eax,%ebx
shl %cl,%eax
L_round:
testl $0x80000000,%eax
jz L_exit
addl $1,%ebx
adcl $0,%edx
jnz L_exit
movl $0x80000000,%edx
incl -4(%ebp)
L_exit:
movl %edx,8(%esi)
movl %ebx,4(%esi)
movl %eax,(%esi)
movl -4(%ebp),%eax
popl %esi
popl %ebx
leave
ret
ENTRY(norm_Xsig)
pushl %ebp
movl %esp,%ebp
pushl %ebx /* Reserve some space */
pushl %ebx
pushl %esi
movl PARAM1,%esi
movl 8(%esi),%edx
movl 4(%esi),%ebx
movl (%esi),%eax
movl $0,-4(%ebp)
orl %edx,%edx /* ms bits */
js L_n_exit /* Already normalized */
jnz L_n_shift_1 /* Shift left 1 - 31 bits */
movl %ebx,%edx
movl %eax,%ebx
xorl %eax,%eax
movl $-32,-4(%ebp)
orl %edx,%edx /* ms bits */
js L_n_exit /* Normalized now */
jnz L_n_shift_1 /* Shift left 1 - 31 bits */
movl %ebx,%edx
movl %eax,%ebx
xorl %eax,%eax
addl $-32,-4(%ebp)
jmp L_n_exit /* Might not be normalized,
but shift no more. */
/* We need to shift left by 1 - 31 bits */
L_n_shift_1:
bsrl %edx,%ecx /* get the required shift in %ecx */
subl $31,%ecx
negl %ecx
subl %ecx,-4(%ebp)
shld %cl,%ebx,%edx
shld %cl,%eax,%ebx
shl %cl,%eax
L_n_exit:
movl %edx,8(%esi)
movl %ebx,4(%esi)
movl %eax,(%esi)
movl -4(%ebp),%eax
popl %esi
popl %ebx
leave
ret