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! bcc 386 floating point routines (version 2) -- Fpushf, Fnegf
! authors: Timothy Murphy (tim@maths.tcd.ie), Bruce Evans
#include "fplib.h"
.extern fpdenormal
! Load float at [ebx], convert to double and push on stack
.globl Fpushf
.align ALIGNMENT
Fpushf:
mov edx,F_HIGH[ebx]
into_Fpushf:
test edx,#F_EXP_MASK ! is exponent 0?
jz exp_x_0
mov ecx,edx ! extract sign
and ecx,#F_SIGN_MASK
and edx,#F_EXP_MASK | F_FRAC_MASK ! extract exponent and fraction
sub eax,eax ! clear lower dword
shrd eax,edx,#D_EXP_BIT-F_EXP_BIT ! shift exponent and fraction to new position
shr edx,#D_EXP_BIT-F_EXP_BIT
add edx,#(D_EXP_BIAS-F_EXP_BIAS) << D_EXP_SHIFT ! adjust exponent bias
or edx,ecx ! include sign
pop ecx
push edx ! upper dword
push eax ! lower dword
jmp ecx ! return
.align ALIGNMENT
exp_x_0:
mov eax,edx
and eax,#F_FRAC_MASK
jnz x_denorm
pop ecx
push eax ! upper dword = 0
push eax ! lower dword = 0
jmp ecx ! return
.align ALIGNMENT
x_denorm:
call fpdenormal
bsr ecx,eax ! zzzz
neg ecx
add ecx,#F_NORM_BIT
shl eax,cl
and eax,#F_FRAC_MASK
neg ecx
add ecx,#D_EXP_BIAS-F_EXP_BIAS+1
shl ecx,#D_EXP_SHIFT
and edx,#F_SIGN_MASK ! assumed same as D_SIGN_MASK
or edx,ecx
sub ecx,ecx
shrd ecx,eax,#D_EXP_BIT-F_EXP_BIT
shr eax,#D_EXP_BIT-F_EXP_BIT
or edx,eax
pop eax
push edx ! upper dword
push ecx ! lower dword
jmp eax ! return
! Fnegf: as Fpushf, but negate double before pushing onto stack
.globl Fnegf
.align ALIGNMENT
Fnegf:
mov edx,F_HIGH[ebx]
xor edx,#F_SIGN_MASK ! toggle sign
jmp into_Fpushf ! join Fpushf
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