BSD 1 development

[unix-history] / px / 30atof.s

/ C library -- ascii to floating

/       f = atof(p)
/       char *p;

ldfps = 170100^tst
stfps = 170200^tst

.globl  _atof

.globl  csv, cret

_atof:
       jsr     r5,csv
       stfps   -(sp)
       ldfps   $200
       movf    fr1,-(sp)
       clr     -(sp)
       clrf    fr0
       clr     r2
       mov     4(r5),r3
1:
       movb    (r3)+,r0
       cmp     $' ,r0
       beq     1b
       cmpb    r0,$'-
       bne     2f
       inc     (sp)
1:
       movb    (r3)+,r0
2:
       sub     $'0,r0
       cmp     r0,$9.
       bhi     2f
       jsr     pc,digit
               br 1b
       inc     r2
       br      1b
2:
       cmpb    r0,$'.-'0
       bne     2f
1:
       movb    (r3)+,r0
       sub     $'0,r0
       cmp     r0,$9.
       bhi     2f
       jsr     pc,digit
               dec r2
       br      1b
2:
       cmpb    r0,$'E-'0
       beq     3f
       cmpb    r0,$'e-'0
       bne     1f
3:
       clr     r4
       clr     r1
       cmpb    (r3),$'-
       bne     3f
       inc     r4
       inc     r3
3:
       movb    (r3)+,r0
       sub     $'0,r0
       cmp     r0,$9.
       bhi     3f
       mul     $10.,r1
       add     r0,r1
       br      3b
3:
       tst     r4
       bne     3f
       neg     r1
3:
       sub     r1,r2
1:
       movf    $one,fr1
       mov     r2,-(sp)
       beq     2f
       bgt     1f
       neg     r2
1:
       cmp     r2,$38.
       blos    1f
       clrf    fr0
       tst     (sp)+
       bmi     out
       movf    $huge,fr0
       br      out
1:
       mulf    $ten,fr1
       sob     r2,1b
2:
       tst     (sp)+
       bge     1f
       divf    fr1,fr0
       br      2f
1:
       mulf    fr1,fr0
       cfcc
       bvc     2f
       movf    $huge,fr0
2:
out:
       tst     (sp)+
       beq     1f
       negf    fr0
1:
       movf    (sp)+,fr1
       ldfps   (sp)+
       jmp     cret
/
/
digit:
       cmpf    $big,fr0
       cfcc
       blt     1f
       mulf    $ten,fr0
       movif   r0,fr1
       addf    fr1,fr0
       rts     pc
1:
       add     $2,(sp)
       rts     pc
/
/
one     = 40200
ten     = 41040
big     = 56200
huge    = 77777