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page ,132 title ftol2 - truncate TOS to 32-bit integer;*** ;ftol2.asm - truncate TOS to 32-bit integer;; Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.;;Purpose:;;Revision History:;; 01/26/01 Phil Lucido; Optimized version from Intel to avoid Pentium FLDCW stalls.;;*******************************************************************************
.xlist include cruntime.inc.list
CODESEG
public _ftol2_ftol2 proc
tmp1 equ <[esp+24]>tmp2 equ <[esp+16]>tmp3 equ <[esp]>
push ebp mov ebp,esp sub esp,32 and esp,0fffffff0h
fld st(0) ; duplicate FPU stack top fst dword ptr tmp1 ; store single to get the sign fistp qword ptr tmp2 ; sto as int fild qword ptr tmp2 ; ld int, cvt to fp mov edx,tmp1 ; get the sign (not fwd problem) mov eax,tmp2 ; low dword of integer test eax,eax je integer_QnaN_or_zero
arg_is_not_integer_QnaN: fsubp st(1),st ; TOS=d-round(d), ; { st(1)=st(1)-st & pop ST} test edx,edx ; whats sign of integer jns positive ; number is negative fstp dword ptr tmp3 ; result of subtraction mov ecx,tmp3 ; dword of diff(single-precision) xor ecx,80000000h add ecx,7fffffffh ; if diff<0 then decrement integer adc eax,0 ; inc eax (add CARRY flag) mov edx,tmp2+4 ; high dword of integer - deferred adc edx,0 jmp localexit
positive: fstp dword ptr tmp3 ; 17-18 result of subtraction mov ecx,tmp3 ; dword of diff(single-precision) add ecx,7fffffffh ; if diff<0 then decrement integer sbb eax,0 ; dec eax (subtract CARRY flag) mov edx,tmp2+4 ; high dword of integer - deferred sbb edx,0 jmp localexit
integer_QnaN_or_zero: ; load the upper 32 bits of the converted integer mov edx,tmp2+4 ; high dword of integer (fwd problem) test edx,7fffffffh jnz arg_is_not_integer_QnaN fstp dword ptr tmp1 fstp dword ptr tmp1
localexit: leave ret
_ftol2 endp
end
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