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|
.file "reg_div.S"
/*---------------------------------------------------------------------------+
| reg_div.S |
| |
| Divide one FPU_REG by another and put the result in a destination FPU_REG.|
| |
| Copyright (C) 1992,1993,1994,1995 |
| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
| Australia. E-mail billm@jacobi.maths.monash.edu.au |
| |
| Call from C as: |
| void reg_div(FPU_REG *a, FPU_REG *b, FPU_REG *dest, |
| unsigned int control_word) |
| |
+---------------------------------------------------------------------------*/
#include "exception.h"
#include "fpu_emu.h"
.text
ENTRY(reg_div)
pushl %ebp
movl %esp,%ebp
#ifndef NON_REENTRANT_FPU
subl $28,%esp /* Needed by divide_kernel */
#endif NON_REENTRANT_FPU
pushl %esi
pushl %edi
pushl %ebx
movl PARAM1,%esi
movl PARAM2,%ebx
movl PARAM3,%edi
movb TAG(%esi),%al
orb TAG(%ebx),%al
jne L_div_special /* Not (both numbers TW_Valid) */
#ifdef DENORM_OPERAND
/* Check for denormals */
cmpl EXP_UNDER,EXP(%esi)
jg xL_arg1_not_denormal
call SYMBOL_NAME(denormal_operand)
orl %eax,%eax
jnz fpu_Arith_exit
xL_arg1_not_denormal:
cmpl EXP_UNDER,EXP(%ebx)
jg xL_arg2_not_denormal
call SYMBOL_NAME(denormal_operand)
orl %eax,%eax
jnz fpu_Arith_exit
xL_arg2_not_denormal:
#endif DENORM_OPERAND
/* Both arguments are TW_Valid */
movb TW_Valid,TAG(%edi)
movb SIGN(%esi),%cl
cmpb %cl,SIGN(%ebx)
setne (%edi) /* Set the sign, requires SIGN_NEG=1, SIGN_POS=0 */
movl EXP(%esi),%edx
movl EXP(%ebx),%eax
subl %eax,%edx
addl EXP_BIAS,%edx
movl %edx,EXP(%edi)
jmp SYMBOL_NAME(divide_kernel)
/*-----------------------------------------------------------------------*/
L_div_special:
cmpb TW_NaN,TAG(%esi) /* A NaN with anything to give NaN */
je L_arg1_NaN
cmpb TW_NaN,TAG(%ebx) /* A NaN with anything to give NaN */
jne L_no_NaN_arg
/* Operations on NaNs */
L_arg1_NaN:
L_arg2_NaN:
pushl %edi /* Destination */
pushl %esi
pushl %ebx /* Ordering is important here */
call SYMBOL_NAME(real_2op_NaN)
jmp LDiv_exit
/* Invalid operations */
L_zero_zero:
L_inf_inf:
pushl %edi /* Destination */
call SYMBOL_NAME(arith_invalid) /* 0/0 or Infinity/Infinity */
jmp LDiv_exit
L_no_NaN_arg:
cmpb TW_Infinity,TAG(%esi)
jne L_arg1_not_inf
cmpb TW_Infinity,TAG(%ebx)
je L_inf_inf /* invalid operation */
cmpb TW_Valid,TAG(%ebx)
je L_inf_valid
#ifdef PARANOID
/* arg2 must be zero or valid */
cmpb TW_Zero,TAG(%ebx)
ja L_unknown_tags
#endif PARANOID
/* Note that p16-9 says that infinity/0 returns infinity */
jmp L_copy_arg1 /* Answer is Inf */
L_inf_valid:
#ifdef DENORM_OPERAND
cmpl EXP_UNDER,EXP(%ebx)
jg L_copy_arg1 /* Answer is Inf */
call SYMBOL_NAME(denormal_operand)
orl %eax,%eax
jnz fpu_Arith_exit
#endif DENORM_OPERAND
jmp L_copy_arg1 /* Answer is Inf */
L_arg1_not_inf:
cmpb TW_Zero,TAG(%ebx) /* Priority to div-by-zero error */
jne L_arg2_not_zero
cmpb TW_Zero,TAG(%esi)
je L_zero_zero /* invalid operation */
#ifdef PARANOID
/* arg1 must be valid */
cmpb TW_Valid,TAG(%esi)
ja L_unknown_tags
#endif PARANOID
/* Division by zero error */
pushl %edi /* destination */
movb SIGN(%esi),%al
xorb SIGN(%ebx),%al
pushl %eax /* lower 8 bits have the sign */
call SYMBOL_NAME(divide_by_zero)
jmp LDiv_exit
L_arg2_not_zero:
cmpb TW_Infinity,TAG(%ebx)
jne L_arg2_not_inf
#ifdef DENORM_OPERAND
cmpb TW_Valid,TAG(%esi)
jne L_return_zero
cmpl EXP_UNDER,EXP(%esi)
jg L_return_zero /* Answer is zero */
call SYMBOL_NAME(denormal_operand)
orl %eax,%eax
jnz fpu_Arith_exit
#endif DENORM_OPERAND
jmp L_return_zero /* Answer is zero */
L_arg2_not_inf:
#ifdef PARANOID
cmpb TW_Zero,TAG(%esi)
jne L_unknown_tags
#endif PARANOID
/* arg1 is zero, arg2 is not Infinity or a NaN */
#ifdef DENORM_OPERAND
cmpl EXP_UNDER,EXP(%ebx)
jg L_copy_arg1 /* Answer is zero */
call SYMBOL_NAME(denormal_operand)
orl %eax,%eax
jnz fpu_Arith_exit
#endif DENORM_OPERAND
L_copy_arg1:
movb TAG(%esi),%ax
movb %ax,TAG(%edi)
movl EXP(%esi),%eax
movl %eax,EXP(%edi)
movl SIGL(%esi),%eax
movl %eax,SIGL(%edi)
movl SIGH(%esi),%eax
movl %eax,SIGH(%edi)
LDiv_set_result_sign:
movb SIGN(%esi),%cl
cmpb %cl,SIGN(%ebx)
jne LDiv_negative_result
movb SIGN_POS,SIGN(%edi)
xorl %eax,%eax /* Valid result */
jmp LDiv_exit
LDiv_negative_result:
movb SIGN_NEG,SIGN(%edi)
xorl %eax,%eax /* Valid result */
LDiv_exit:
#ifndef NON_REENTRANT_FPU
leal -40(%ebp),%esp
#else
leal -12(%ebp),%esp
#endif NON_REENTRANT_FPU
popl %ebx
popl %edi
popl %esi
leave
ret
L_return_zero:
xorl %eax,%eax
movl %eax,SIGH(%edi)
movl %eax,SIGL(%edi)
movl EXP_UNDER,EXP(%edi)
movb TW_Zero,TAG(%edi)
jmp LDiv_set_result_sign
#ifdef PARANOID
L_unknown_tags:
pushl EX_INTERNAL | 0x208
call EXCEPTION
/* Generate a NaN for unknown tags */
movl SYMBOL_NAME(CONST_QNaN),%eax
movl %eax,(%edi)
movl SYMBOL_NAME(CONST_QNaN)+4,%eax
movl %eax,SIGL(%edi)
movl SYMBOL_NAME(CONST_QNaN)+8,%eax
movl %eax,SIGH(%edi)
jmp LDiv_exit /* %eax is nz */
#endif PARANOID
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