usr/src/lib/libnm/log.s

# double log(arg) ; natural logarithm
# double log10(arg); base 10 log
# double arg
# if(arg<=0){ errno=EDOM; return(-1.7e+38); }
# nat. log computed from Hart&Cheney LOGE 2706 D=22.1
# J F Jarvis August 3, 1978
.set    EDOM,33
.globl  _log
.globl  _log10
.globl  _errno
.text
.align  1
_log10:
        .word   0x0
        movd    4(ap),-(sp)
        calls   $2,_log
        muld2   log10e,r0
        ret
.align  1
_log:
        .word   0x07c0
        movd    4(ap),r0
        jgtr    range
        movl    $EDOM,_errno
        movd    $0d-1.7e+38,r0  # machine dept max neg
        ret
range:
        extzv   $7,$8,r0,r10    # r10 = exp(arg)+128
        insv    $128,$7,$8,r0   # r0,r1: 0.5<=frac(arg)<1.0
        cmpd    r0,sqrt2d2
        jgeq    comp
        insv    $129,$7,$8,r0   # frac *= 2
        decl    r10                             # exp -= 1
comp:
        subl2   $128,r10        # signed exp for scaled arg
        subd3   $0d1.0e+0,r0,r6 # Hart&cheney LOGE 2706
        addd2   $0d1.0e+0,r0
        divd2   r0,r6   # r6,r7= (frac-1)/(frac+1)
        muld3   r6,r6,r8
        polyd   r8,$3,pcoef
        muld2   r0,r6
        polyd   r8,$4,qcoef
        divd3   r0,r6,r0
        cvtld   r10,r2
        muld2   log2,r2 # r2,r3= loge(2**exp)
        addd2   r2,r0
        ret
.data
.align  2
pcoef:
        .double 0d-0.24550691103445385056e+2
        .double 0d0.23616053565907671809e+3
        .double 0d-0.54904361859132995001e+3
        .double 0d0.35621151669903912407e+3
qcoef:
        .double 0d0.10e+1
        .double 0d-0.35526251110400238735e+2
        .double 0d0.19375591463035879517e+3
        .double 0d-0.33389039541217149928e+3
        .double 0d0.17810575834951956204e+3
log10e:
        .double 0d0.43429448190325182765e+0
sqrt2d2:
        .double 0d0.70710678118654752440e+0
log2:
        .double 0d0.69314718055994530941e+0