Source code of Windows XP (NT5)
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;***
;
; Copyright (c) 1984-2001, Microsoft Corporation. All rights reserved.
;
; Revision History:
; 01-26-01 PML Pentium4 merge.
; 02-25-01 PML Fix pow(+/-0,-denorm)
;
;*******************************************************************************
.xlist
include cruntime.inc
include elem87.inc
.list
_FUNC_ equ <pow>
_FUNC_DEF_ equ <_pow_default>
_FUNC_P4_ equ <_pow_pentium4>
_FUNC_P4_EXTERN_ equ 1
include disp_pentium4.inc
_FUNC_ equ <_CIpow>
_FUNC_DEF_ equ <_CIpow_default>
_FUNC_P4_ equ <_CIpow_pentium4>
include disp_pentium4.inc
.data
globalQ _half, 03fe0000000000000R
POW_name db 'pow',0
extrn _infinity:tbyte
extrn _indefinite:tbyte
extrn __fastflag:dword
CODESEG
extrn _startTwoArgErrorHandling:near
extrn _fload_withFB:near
extrn _convertTOStoQNaN:near
extrn _checkTOS_withFB:near
extrn _check_range_exit:near
extrn _fast_exit:near
extrn _load_CW:near
extrn _powhlp:near
extrn _twoToTOS:near
; arg1(base) arg2(exponent) ErrorType result
;-----------------------------------------------------------
;infinity not NaN called powhlp()
;not NaN infinity called powhlp()
;QNaN not SNaN DOMAIN_QNAN QNaN
;SNaN any DOMAIN
;
;*0 *0 - 1
;*0 positive,not odd - +0
;+0 positive, odd - +0
;-0 positive, odd - -0
;*0 negative,not odd SING infinity
;+0 negative, odd SING infinity
;-0 negative, odd SING -infinity
;negative non-integer DOMAIN indefinite
;indefinite is like QNaN
;denormal(53) fld converts it to normal (64 bits)
;
; * in table above stands for both + and -
;
; if exponent field of result is 0, error type is set to UNDERFLOW
; if result is infinity, error type is set to OVERFLOW
public _CIpow_default,_pow_default
_CIpow_default proc
sub esp,2*DBLSIZE+4 ; prepare place for argument
fxch st(1)
fstp qword ptr [esp] ; base
fst qword ptr [esp+8] ; exponent
mov eax,[esp+12] ; high dword of exponent
call start
add esp,2*DBLSIZE+4 ; clean stack
ret
_pow_default label proc
lea edx,[esp+12] ; load exponent(arg2)
call _fload_withFB
start:
mov ecx,eax ; make copy of eax
push eax ; allocate space for Control Word
fstcw [esp] ; store Control Word
cmp word ptr[esp],default_CW
je CW_is_set_to_default
call _load_CW ; edx is destroyed
CW_is_set_to_default:
; at this point we have on stack: cw(4), ret_addr(4), arg1(8bytes), arg2(8bytes)
and ecx,7ff00000H
lea edx,[esp+8] ; edx points to arg1(base)
cmp ecx,7ff00000H
je special_exponent
call _fload_withFB ; edx already initialized
jz special_base
test eax,7ff00000H
jz test_if_we_have_zero_base
base_is_not_zero:
mov cl,[esp+15] ; cl will contain sign
and cl,80H ; test sign of base
jnz test_if_exp_is_int
normal: ; denormal is like normal
fyl2x ; compute y*log2(x)
call _twoToTOS
cmp cl,1 ; power was odd and base<0 ?
jnz exit
fchs ; if yes, we should change sign
exit:
cmp __fastflag,0
jnz _fast_exit
; prepare in registers arguments for math_exit
lea ecx,[POW_name]
mov edx,OP_POW
jmp _check_range_exit
_ErrorHandling:
cmp __fastflag,0
jnz _fast_exit
lea ecx,[POW_name]
mov edx,OP_POW
call _startTwoArgErrorHandling
pop edx ; remove saved CW from stack
ret
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; some special cases
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; 1.One of arguments is NaN
exponent_is_NAN:
lea edx,[esp+8] ; pointer to arg1(base)
call _fload_withFB ; load arg1 to FPU stack
test byte ptr[esp+22],08H ; test if arg2(exponent) is SNaN
jnz SNaN_detected
inc ecx ; ecx!=0 when one of args is QNaN
jmp test_base
SNaN_detected:
fadd
mov eax,DOMAIN
jmp _ErrorHandling
base_is_NAN:
test byte ptr[esp+14],08H ; is it SNaN
jnz SNaN_detected
one_of_args_is_QNaN:
fadd ; one of args is QNaN, and second is not SNaN
mov eax,DOMAIN_QNAN
jmp _ErrorHandling
special_base:
; both arguments are loaded to FPU stack
xor ecx,ecx
jmp test_base
special_exponent:
; only one argument is loaded to FPU stack
xor ecx,ecx ; we use ecx to set flags
and eax,000fffffH ; eax=high
or eax,[esp+16] ; test whether mantissa is zero
jne exponent_is_NAN
lea edx,[esp+8] ; pointer to arg1(base)
call _fload_withFB ; load arg1(base) to FPU stack
test_base: ; arg2 may be inf, QNaN or normal
; both arguments are loaded to FPU stack
mov eax,[esp+12] ; arg1 high
mov edx,eax
and eax,7ff00000H
and edx,000fffffH ; test mantissa of arg2
cmp eax,7ff00000H
jne end_of_tests
or edx,[esp+8]
jnz base_is_NAN ; arg1 is NaN,
end_of_tests:
test ecx,ecx
jnz one_of_args_is_QNaN ; base is QNaN
; one of args is infinity and second is not NaN. In this case we use powhlp()
;_usepowhlp
sub esp, SBUFSIZE+8 ; get storage for _retval and savebuf
mov ecx, esp
push ecx ; push address for result
sub esp, 16
fstp qword ptr [esp]
fstp qword ptr [esp+8]
fsave [ecx+8]
call _powhlp
add esp, 16 ; clear arguments if _cdecl.
pop ecx
frstor [ecx+8]
fld qword ptr [ecx] ; load result on the NDP stack
add esp, SBUFSIZE+8 ; get rid of storage
test eax,eax
jz _fast_exit
mov eax,DOMAIN
jmp _ErrorHandling
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; 2. Base has zero exponent field
;
test_if_we_have_zero_base:
mov eax,[esp+12]
and eax,000fffffH
or eax,[esp+8]
jnz base_is_not_zero
; at this point we have two arguments on FPU stack.
; We know that TOS is zero, and arg2 is not special.
; We disinguish 3 cases:
; (1) exponent is zero
; (2) exponent is odd
; (3) none of above
fstp st(0) ; remove zero from FPU stack
mov eax,[esp+20] ; test if arg2 is also zero
and eax,7fffffffh
or eax,[esp+16]
jz zero_to_zero
; check whether exponent is odd
call _test_whether_TOS_is_int
; cl=1 if exponent is odd, 2 - if even and 0 otherwise
mov ch,[esp+15]
shr ch,7 ; ch==1 iff base is negative
test [esp+23],80H ; check sign of exponent
jz exp_is_positive
; exponent is negative
fld [_infinity]
test cl,ch
jz ret_inf
fchs ; base <0 and exponent is negative odd
ret_inf:
mov eax,SING
jmp _ErrorHandling
exp_is_positive: ; eax=error_code
fldz
test cl,ch
jz _fast_exit
fchs ; base <0 and exponent positive is odd
jmp _fast_exit ; return -0.0
zero_to_zero: ; arg1 and arg2 are zero
fstp st(0) ; remove useless argument from FPU stack
fld1
jmp _fast_exit
;;;;;;;;;;;;;;;;;;;;;;;;;;;
;3. Base is negative.
;
; If exponent is not integer it's a DOMAIN error
;
test_if_exp_is_int:
fld st(1)
call _test_whether_TOS_is_int
fchs
test cl,cl
jnz normal
fstp st(0)
fstp st(0)
fld [_indefinite]
mov eax,DOMAIN
jmp _ErrorHandling
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
; _test_whether_TOS_is_int
;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; returns in cl : 0,1,2 if TOS is non-int, odd int or even int respectively
;
_test_whether_TOS_is_int:
fld st(0) ; duplicate stack top
frndint
fcomp ; is TOS integer???
mov cl,0 ; prepare return value
fstsw ax
sahf
jne _not_int ; TOS is not integer
fmul [_half]
inc cl ; cl>0, when exponent is integer
fld st(0) ; (exponent/2)
frndint
fcompp ; check if (exponent/2)==(int)(exponent/2)
fstsw ax
sahf
jne _odd
inc cl ; sign that exponent is even
_odd:
ret
_not_int:
fstp st(0)
ret
_CIpow_default endp
end