368 lines
9.9 KiB
ArmAsm
368 lines
9.9 KiB
ArmAsm
|
/* SPDX-License-Identifier: GPL-2.0 */
|
||
|
|
.file "div_Xsig.S"
|
||
|
|
/*---------------------------------------------------------------------------+
|
||
|
|
| div_Xsig.S |
|
||
|
|
| |
|
||
|
|
| Division subroutine for 96 bit quantities |
|
||
|
|
| |
|
||
|
|
| Copyright (C) 1994,1995 |
|
||
|
|
| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
|
||
|
|
| Australia. E-mail billm@jacobi.maths.monash.edu.au |
|
||
|
|
| |
|
||
|
|
| |
|
||
|
|
+---------------------------------------------------------------------------*/
|
||
|
|
|
||
|
|
/*---------------------------------------------------------------------------+
|
||
|
|
| Divide the 96 bit quantity pointed to by a, by that pointed to by b, and |
|
||
|
|
| put the 96 bit result at the location d. |
|
||
|
|
| |
|
||
|
|
| The result may not be accurate to 96 bits. It is intended for use where |
|
||
|
|
| a result better than 64 bits is required. The result should usually be |
|
||
|
|
| good to at least 94 bits. |
|
||
|
|
| The returned result is actually divided by one half. This is done to |
|
||
|
|
| prevent overflow. |
|
||
|
|
| |
|
||
|
|
| .aaaaaaaaaaaaaa / .bbbbbbbbbbbbb -> .dddddddddddd |
|
||
|
|
| |
|
||
|
|
| void div_Xsig(Xsig *a, Xsig *b, Xsig *dest) |
|
||
|
|
| |
|
||
|
|
+---------------------------------------------------------------------------*/
|
||
|
|
|
||
|
|
#include "exception.h"
|
||
|
|
#include "fpu_emu.h"
|
||
|
|
|
||
|
|
|
||
|
|
#define XsigLL(x) (x)
|
||
|
|
#define XsigL(x) 4(x)
|
||
|
|
#define XsigH(x) 8(x)
|
||
|
|
|
||
|
|
|
||
|
|
#ifndef NON_REENTRANT_FPU
|
||
|
|
/*
|
||
|
|
Local storage on the stack:
|
||
|
|
Accumulator: FPU_accum_3:FPU_accum_2:FPU_accum_1:FPU_accum_0
|
||
|
|
*/
|
||
|
|
#define FPU_accum_3 -4(%ebp)
|
||
|
|
#define FPU_accum_2 -8(%ebp)
|
||
|
|
#define FPU_accum_1 -12(%ebp)
|
||
|
|
#define FPU_accum_0 -16(%ebp)
|
||
|
|
#define FPU_result_3 -20(%ebp)
|
||
|
|
#define FPU_result_2 -24(%ebp)
|
||
|
|
#define FPU_result_1 -28(%ebp)
|
||
|
|
|
||
|
|
#else
|
||
|
|
.data
|
||
|
|
/*
|
||
|
|
Local storage in a static area:
|
||
|
|
Accumulator: FPU_accum_3:FPU_accum_2:FPU_accum_1:FPU_accum_0
|
||
|
|
*/
|
||
|
|
.align 4,0
|
||
|
|
FPU_accum_3:
|
||
|
|
.long 0
|
||
|
|
FPU_accum_2:
|
||
|
|
.long 0
|
||
|
|
FPU_accum_1:
|
||
|
|
.long 0
|
||
|
|
FPU_accum_0:
|
||
|
|
.long 0
|
||
|
|
FPU_result_3:
|
||
|
|
.long 0
|
||
|
|
FPU_result_2:
|
||
|
|
.long 0
|
||
|
|
FPU_result_1:
|
||
|
|
.long 0
|
||
|
|
#endif /* NON_REENTRANT_FPU */
|
||
|
|
|
||
|
|
|
||
|
|
.text
|
||
|
|
SYM_FUNC_START(div_Xsig)
|
||
|
|
pushl %ebp
|
||
|
|
movl %esp,%ebp
|
||
|
|
#ifndef NON_REENTRANT_FPU
|
||
|
|
subl $28,%esp
|
||
|
|
#endif /* NON_REENTRANT_FPU */
|
||
|
|
|
||
|
|
pushl %esi
|
||
|
|
pushl %edi
|
||
|
|
pushl %ebx
|
||
|
|
|
||
|
|
movl PARAM1,%esi /* pointer to num */
|
||
|
|
movl PARAM2,%ebx /* pointer to denom */
|
||
|
|
|
||
|
|
#ifdef PARANOID
|
||
|
|
testl $0x80000000, XsigH(%ebx) /* Divisor */
|
||
|
|
je L_bugged
|
||
|
|
#endif /* PARANOID */
|
||
|
|
|
||
|
|
|
||
|
|
/*---------------------------------------------------------------------------+
|
||
|
|
| Divide: Return arg1/arg2 to arg3. |
|
||
|
|
| |
|
||
|
|
| The maximum returned value is (ignoring exponents) |
|
||
|
|
| .ffffffff ffffffff |
|
||
|
|
| ------------------ = 1.ffffffff fffffffe |
|
||
|
|
| .80000000 00000000 |
|
||
|
|
| and the minimum is |
|
||
|
|
| .80000000 00000000 |
|
||
|
|
| ------------------ = .80000000 00000001 (rounded) |
|
||
|
|
| .ffffffff ffffffff |
|
||
|
|
| |
|
||
|
|
+---------------------------------------------------------------------------*/
|
||
|
|
|
||
|
|
/* Save extended dividend in local register */
|
||
|
|
|
||
|
|
/* Divide by 2 to prevent overflow */
|
||
|
|
clc
|
||
|
|
movl XsigH(%esi),%eax
|
||
|
|
rcrl %eax
|
||
|
|
movl %eax,FPU_accum_3
|
||
|
|
movl XsigL(%esi),%eax
|
||
|
|
rcrl %eax
|
||
|
|
movl %eax,FPU_accum_2
|
||
|
|
movl XsigLL(%esi),%eax
|
||
|
|
rcrl %eax
|
||
|
|
movl %eax,FPU_accum_1
|
||
|
|
movl $0,%eax
|
||
|
|
rcrl %eax
|
||
|
|
movl %eax,FPU_accum_0
|
||
|
|
|
||
|
|
movl FPU_accum_2,%eax /* Get the current num */
|
||
|
|
movl FPU_accum_3,%edx
|
||
|
|
|
||
|
|
/*----------------------------------------------------------------------*/
|
||
|
|
/* Initialization done.
|
||
|
|
Do the first 32 bits. */
|
||
|
|
|
||
|
|
/* We will divide by a number which is too large */
|
||
|
|
movl XsigH(%ebx),%ecx
|
||
|
|
addl $1,%ecx
|
||
|
|
jnc LFirst_div_not_1
|
||
|
|
|
||
|
|
/* here we need to divide by 100000000h,
|
||
|
|
i.e., no division at all.. */
|
||
|
|
mov %edx,%eax
|
||
|
|
jmp LFirst_div_done
|
||
|
|
|
||
|
|
LFirst_div_not_1:
|
||
|
|
divl %ecx /* Divide the numerator by the augmented
|
||
|
|
denom ms dw */
|
||
|
|
|
||
|
|
LFirst_div_done:
|
||
|
|
movl %eax,FPU_result_3 /* Put the result in the answer */
|
||
|
|
|
||
|
|
mull XsigH(%ebx) /* mul by the ms dw of the denom */
|
||
|
|
|
||
|
|
subl %eax,FPU_accum_2 /* Subtract from the num local reg */
|
||
|
|
sbbl %edx,FPU_accum_3
|
||
|
|
|
||
|
|
movl FPU_result_3,%eax /* Get the result back */
|
||
|
|
mull XsigL(%ebx) /* now mul the ls dw of the denom */
|
||
|
|
|
||
|
|
subl %eax,FPU_accum_1 /* Subtract from the num local reg */
|
||
|
|
sbbl %edx,FPU_accum_2
|
||
|
|
sbbl $0,FPU_accum_3
|
||
|
|
je LDo_2nd_32_bits /* Must check for non-zero result here */
|
||
|
|
|
||
|
|
#ifdef PARANOID
|
||
|
|
jb L_bugged_1
|
||
|
|
#endif /* PARANOID */
|
||
|
|
|
||
|
|
/* need to subtract another once of the denom */
|
||
|
|
incl FPU_result_3 /* Correct the answer */
|
||
|
|
|
||
|
|
movl XsigL(%ebx),%eax
|
||
|
|
movl XsigH(%ebx),%edx
|
||
|
|
subl %eax,FPU_accum_1 /* Subtract from the num local reg */
|
||
|
|
sbbl %edx,FPU_accum_2
|
||
|
|
|
||
|
|
#ifdef PARANOID
|
||
|
|
sbbl $0,FPU_accum_3
|
||
|
|
jne L_bugged_1 /* Must check for non-zero result here */
|
||
|
|
#endif /* PARANOID */
|
||
|
|
|
||
|
|
/*----------------------------------------------------------------------*/
|
||
|
|
/* Half of the main problem is done, there is just a reduced numerator
|
||
|
|
to handle now.
|
||
|
|
Work with the second 32 bits, FPU_accum_0 not used from now on */
|
||
|
|
LDo_2nd_32_bits:
|
||
|
|
movl FPU_accum_2,%edx /* get the reduced num */
|
||
|
|
movl FPU_accum_1,%eax
|
||
|
|
|
||
|
|
/* need to check for possible subsequent overflow */
|
||
|
|
cmpl XsigH(%ebx),%edx
|
||
|
|
jb LDo_2nd_div
|
||
|
|
ja LPrevent_2nd_overflow
|
||
|
|
|
||
|
|
cmpl XsigL(%ebx),%eax
|
||
|
|
jb LDo_2nd_div
|
||
|
|
|
||
|
|
LPrevent_2nd_overflow:
|
||
|
|
/* The numerator is greater or equal, would cause overflow */
|
||
|
|
/* prevent overflow */
|
||
|
|
subl XsigL(%ebx),%eax
|
||
|
|
sbbl XsigH(%ebx),%edx
|
||
|
|
movl %edx,FPU_accum_2
|
||
|
|
movl %eax,FPU_accum_1
|
||
|
|
|
||
|
|
incl FPU_result_3 /* Reflect the subtraction in the answer */
|
||
|
|
|
||
|
|
#ifdef PARANOID
|
||
|
|
je L_bugged_2 /* Can't bump the result to 1.0 */
|
||
|
|
#endif /* PARANOID */
|
||
|
|
|
||
|
|
LDo_2nd_div:
|
||
|
|
cmpl $0,%ecx /* augmented denom msw */
|
||
|
|
jnz LSecond_div_not_1
|
||
|
|
|
||
|
|
/* %ecx == 0, we are dividing by 1.0 */
|
||
|
|
mov %edx,%eax
|
||
|
|
jmp LSecond_div_done
|
||
|
|
|
||
|
|
LSecond_div_not_1:
|
||
|
|
divl %ecx /* Divide the numerator by the denom ms dw */
|
||
|
|
|
||
|
|
LSecond_div_done:
|
||
|
|
movl %eax,FPU_result_2 /* Put the result in the answer */
|
||
|
|
|
||
|
|
mull XsigH(%ebx) /* mul by the ms dw of the denom */
|
||
|
|
|
||
|
|
subl %eax,FPU_accum_1 /* Subtract from the num local reg */
|
||
|
|
sbbl %edx,FPU_accum_2
|
||
|
|
|
||
|
|
#ifdef PARANOID
|
||
|
|
jc L_bugged_2
|
||
|
|
#endif /* PARANOID */
|
||
|
|
|
||
|
|
movl FPU_result_2,%eax /* Get the result back */
|
||
|
|
mull XsigL(%ebx) /* now mul the ls dw of the denom */
|
||
|
|
|
||
|
|
subl %eax,FPU_accum_0 /* Subtract from the num local reg */
|
||
|
|
sbbl %edx,FPU_accum_1 /* Subtract from the num local reg */
|
||
|
|
sbbl $0,FPU_accum_2
|
||
|
|
|
||
|
|
#ifdef PARANOID
|
||
|
|
jc L_bugged_2
|
||
|
|
#endif /* PARANOID */
|
||
|
|
|
||
|
|
jz LDo_3rd_32_bits
|
||
|
|
|
||
|
|
#ifdef PARANOID
|
||
|
|
cmpl $1,FPU_accum_2
|
||
|
|
jne L_bugged_2
|
||
|
|
#endif /* PARANOID */
|
||
|
|
|
||
|
|
/* need to subtract another once of the denom */
|
||
|
|
movl XsigL(%ebx),%eax
|
||
|
|
movl XsigH(%ebx),%edx
|
||
|
|
subl %eax,FPU_accum_0 /* Subtract from the num local reg */
|
||
|
|
sbbl %edx,FPU_accum_1
|
||
|
|
sbbl $0,FPU_accum_2
|
||
|
|
|
||
|
|
#ifdef PARANOID
|
||
|
|
jc L_bugged_2
|
||
|
|
jne L_bugged_2
|
||
|
|
#endif /* PARANOID */
|
||
|
|
|
||
|
|
addl $1,FPU_result_2 /* Correct the answer */
|
||
|
|
adcl $0,FPU_result_3
|
||
|
|
|
||
|
|
#ifdef PARANOID
|
||
|
|
jc L_bugged_2 /* Must check for non-zero result here */
|
||
|
|
#endif /* PARANOID */
|
||
|
|
|
||
|
|
/*----------------------------------------------------------------------*/
|
||
|
|
/* The division is essentially finished here, we just need to perform
|
||
|
|
tidying operations.
|
||
|
|
Deal with the 3rd 32 bits */
|
||
|
|
LDo_3rd_32_bits:
|
||
|
|
/* We use an approximation for the third 32 bits.
|
||
|
|
To take account of the 3rd 32 bits of the divisor
|
||
|
|
(call them del), we subtract del * (a/b) */
|
||
|
|
|
||
|
|
movl FPU_result_3,%eax /* a/b */
|
||
|
|
mull XsigLL(%ebx) /* del */
|
||
|
|
|
||
|
|
subl %edx,FPU_accum_1
|
||
|
|
|
||
|
|
/* A borrow indicates that the result is negative */
|
||
|
|
jnb LTest_over
|
||
|
|
|
||
|
|
movl XsigH(%ebx),%edx
|
||
|
|
addl %edx,FPU_accum_1
|
||
|
|
|
||
|
|
subl $1,FPU_result_2 /* Adjust the answer */
|
||
|
|
sbbl $0,FPU_result_3
|
||
|
|
|
||
|
|
/* The above addition might not have been enough, check again. */
|
||
|
|
movl FPU_accum_1,%edx /* get the reduced num */
|
||
|
|
cmpl XsigH(%ebx),%edx /* denom */
|
||
|
|
jb LDo_3rd_div
|
||
|
|
|
||
|
|
movl XsigH(%ebx),%edx
|
||
|
|
addl %edx,FPU_accum_1
|
||
|
|
|
||
|
|
subl $1,FPU_result_2 /* Adjust the answer */
|
||
|
|
sbbl $0,FPU_result_3
|
||
|
|
jmp LDo_3rd_div
|
||
|
|
|
||
|
|
LTest_over:
|
||
|
|
movl FPU_accum_1,%edx /* get the reduced num */
|
||
|
|
|
||
|
|
/* need to check for possible subsequent overflow */
|
||
|
|
cmpl XsigH(%ebx),%edx /* denom */
|
||
|
|
jb LDo_3rd_div
|
||
|
|
|
||
|
|
/* prevent overflow */
|
||
|
|
subl XsigH(%ebx),%edx
|
||
|
|
movl %edx,FPU_accum_1
|
||
|
|
|
||
|
|
addl $1,FPU_result_2 /* Reflect the subtraction in the answer */
|
||
|
|
adcl $0,FPU_result_3
|
||
|
|
|
||
|
|
LDo_3rd_div:
|
||
|
|
movl FPU_accum_0,%eax
|
||
|
|
movl FPU_accum_1,%edx
|
||
|
|
divl XsigH(%ebx)
|
||
|
|
|
||
|
|
movl %eax,FPU_result_1 /* Rough estimate of third word */
|
||
|
|
|
||
|
|
movl PARAM3,%esi /* pointer to answer */
|
||
|
|
|
||
|
|
movl FPU_result_1,%eax
|
||
|
|
movl %eax,XsigLL(%esi)
|
||
|
|
movl FPU_result_2,%eax
|
||
|
|
movl %eax,XsigL(%esi)
|
||
|
|
movl FPU_result_3,%eax
|
||
|
|
movl %eax,XsigH(%esi)
|
||
|
|
|
||
|
|
L_exit:
|
||
|
|
popl %ebx
|
||
|
|
popl %edi
|
||
|
|
popl %esi
|
||
|
|
|
||
|
|
leave
|
||
|
|
RET
|
||
|
|
|
||
|
|
|
||
|
|
#ifdef PARANOID
|
||
|
|
/* The logic is wrong if we got here */
|
||
|
|
L_bugged:
|
||
|
|
pushl EX_INTERNAL|0x240
|
||
|
|
call EXCEPTION
|
||
|
|
pop %ebx
|
||
|
|
jmp L_exit
|
||
|
|
|
||
|
|
L_bugged_1:
|
||
|
|
pushl EX_INTERNAL|0x241
|
||
|
|
call EXCEPTION
|
||
|
|
pop %ebx
|
||
|
|
jmp L_exit
|
||
|
|
|
||
|
|
L_bugged_2:
|
||
|
|
pushl EX_INTERNAL|0x242
|
||
|
|
call EXCEPTION
|
||
|
|
pop %ebx
|
||
|
|
jmp L_exit
|
||
|
|
#endif /* PARANOID */
|
||
|
|
SYM_FUNC_END(div_Xsig)
|