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Annotation of coherent/b/lib/libc/crt/i386/frexp.s, revision 1.1

1.1     ! root        1: //////////
        !             2: / libc/crt/i386/frexp.s
        !             3: / i386 C runtime library.
        !             4: / IEEE software floating point support.
        !             5: / i386 IEEE software floating point library.
        !             6: / frexp()
        !             7: //////////
        !             8: 
        !             9: //////////
        !            10: / double
        !            11: / frexp(real, ep) double real; int *ep;
        !            12: /
        !            13: / Store exponent e through ep and return mantissa m,
        !            14: / where real = m * 2^e, 1/2 <= |m| < 1.
        !            15: //////////
        !            16: 
        !            17:        .globl  frexp
        !            18: 
        !            19: real   .equ    4
        !            20: ep     .equ    real+8
        !            21: EXPMASK        .equ    0x7FF00000
        !            22: DEFEXP .equ    1022
        !            23: 
        !            24: frexp:
        !            25:        movl    %edx, real+4(%esp)      / real sign/exp to EDX
        !            26:        movl    %ecx, $EXPMASK
        !            27:        andl    %ecx, %edx              / extract exponent bits in ECX
        !            28:        jnz     ?L0                     / watch for -0.0
        !            29:        movl    %edx, %ecx              / exponent 0, zap sign bit in case -0.0
        !            30: 
        !            31: ?L0:
        !            32:        xorl    %edx, %ecx              / mask off exponent in EDX
        !            33:        orl     %edx, $DEFEXP<<20       / and replace with new exponent
        !            34:        shrl    %ecx, $20               / unshifted exponent in ECX
        !            35:        subl    %ecx, $DEFEXP           / unbiased
        !            36:        movl    %eax, ep(%esp)          / ep to EAX
        !            37:        movl    (%eax), %ecx            / store exponent
        !            38:        movl    %eax, real(%esp)        / fetch low mantissa dword to EAX
        !            39:        ret
        !            40: 
        !            41: / end of libc/crt/i386/frexp.s

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