Return to divf.x CVS log

Up to [Power 6/32 Unix Tahoe 4.2BSD] / cci / usr / src / lib / libc / tahoe / gen

Annotation of cci/usr/src/lib/libc/tahoe/gen/divf.x, revision 1.1

1.1     ! root        1: 
        !             2: #include       <machine/fp.h>
        !             3: 
        !             4: 
        !             5:                        # here we count from 0 not from 1 as in fp.h
        !             6: #define        HIDDEN  23      
        !             7: 
        !             8:        .text
        !             9:        .globl  Xdivf
        !            10: _divf:
        !            11: Xdivf: .word   0xffc
        !            12:        clrl    r1
        !            13:        clrl    r3              # r3 - sign: 0 for positive,1 for negative.
        !            14:        movl    4(fp),r0
        !            15:        jgeq    1f
        !            16:        movl    $1,r3
        !            17: 1:     movl    12(fp),r2
        !            18:        jgeq    2f
        !            19:        bbc     $0,r3,1f        # seconed operand is negative.
        !            20:        clrl    r3              # if first was negative, make result positive.
        !            21:        jmp     2f
        !            22: 1:     movl    $1,r3           # if first was positive, make result negative.
        !            23: 2:     andl2   $EXPMASK,r0     # compute first 'pure'exponent.
        !            24:        jeql    is_res1
        !            25:        shrl    $EXPSHIFT,r0,r0
        !            26:        subl2   $BIAS,r0        
        !            27:        andl2   $EXPMASK,r2     # compute seconed 'pure'exponent.
        !            28:        jeql    is_res2
        !            29:        shrl    $EXPSHIFT,r2,r2
        !            30:        subl2   $BIAS,r2
        !            31:        subl3   r2,r0,r2        # subtruct the exponents.
        !            32:        addl2   $BIAS,r2
        !            33:        jleq    underf
        !            34:                                # normalization can make the exp. smaller.
        !            35:  #
        !            36:  #     We have the sign in r3,the exponent in r2,now is the time to
        !            37:  #     perform the division...
        !            38:  #
        !            39:        # fetch dividend. (r0)
        !            40:        andl3   $(0!(EXPMASK | SIGNBIT)),4(fp),r0
        !            41:        orl2    $(0!CLEARHID),r0
        !            42:        clrl    r1
        !            43:  
        !            44:        # fetch divisor : (r6)
        !            45:        andl3   $(0!(EXPMASK | SIGNBIT)),12(fp),r6
        !            46:        orl2    $(0!CLEARHID),r6
        !            47: 
        !            48:        shll    $2,r6,r6        # make the divisor bigger so we will not
        !            49:                                # get overflow at the divission.
        !            50:        ediv    r6,r0,r0,r7     # quo to r0, rem to r7
        !            51:        subl2   $6,r2           # to compensate for: normalization (-24),
        !            52:                                # ediv (+32), shifting r6 (-2).
        !            53:        
        !            54: over:
        !            55:        callf   $4,fnorm        # we can use fnorm because we have data
        !            56:                                # at r1 as well.(sfnorm takes care only 
        !            57:                                # of r0).
        !            58: sign:
        !            59: 1:     bbc     $0,r3,done
        !            60:        orl2    $SIGNBIT,r0
        !            61: done:  ret
        !            62: 
        !            63: is_res1:
        !            64:        bbc     $31,4(fp),retz
        !            65:        callf   $4,sfpresop
        !            66:        ret
        !            67: is_res2:
        !            68:        bbc     $31,12(fp),z_div
        !            69:        callf   $4,sfpresop
        !            70:        ret
        !            71: retz:
        !            72:          clrl  r0
        !            73:          ret
        !            74: underf:
        !            75:        callf   $4,sfpunder
        !            76:        ret
        !            77: z_div:
        !            78:        callf   $4,sfpzdiv
        !            79:        ret

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.