diff options
Diffstat (limited to 'libc/i386fp/fpushf.x')
| -rw-r--r-- | libc/i386fp/fpushf.x | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/libc/i386fp/fpushf.x b/libc/i386fp/fpushf.x new file mode 100644 index 0000000..7cb2f8d --- /dev/null +++ b/libc/i386fp/fpushf.x @@ -0,0 +1,74 @@ +! 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 |