projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 6b92951c KT |
1 | ldfps = 170100^tst |
| 2 | stfps = 170200^tst | |
| 3 | / | |
| 4 | / sqrt replaces the f.p. number in fr0 by its | |
| 5 | / square root. newton's method | |
| 6 | / | |
| 7 | .globl sqrt, _sqrt | |
| 8 | / | |
| 9 | / | |
| 10 | _sqrt: | |
| 11 | mov r5,-(sp) | |
| 12 | mov sp,r5 | |
| 13 | movf 4(r5),fr0 | |
| 14 | jsr pc,sqrt | |
| 15 | mov (sp)+,r5 | |
| 16 | rts pc | |
| 17 | ||
| 18 | sqrt: | |
| 19 | tstf fr0 | |
| 20 | cfcc | |
| 21 | bne 1f | |
| 22 | clc | |
| 23 | rts pc /sqrt(0) | |
| 24 | 1: | |
| 25 | bgt 1f | |
| 26 | clrf fr0 | |
| 27 | sec | |
| 28 | rts pc / sqrt(-a) | |
| 29 | 1: | |
| 30 | mov r0,-(sp) | |
| 31 | stfps -(sp) | |
| 32 | mov (sp),r0 | |
| 33 | bic $!200,r0 / retain mode | |
| 34 | ldfps r0 | |
| 35 | movf fr1,-(sp) | |
| 36 | movf fr2,-(sp) | |
| 37 | / | |
| 38 | movf fr0,fr1 | |
| 39 | movf fr0,-(sp) | |
| 40 | asr (sp) | |
| 41 | add $20100,(sp) | |
| 42 | movf (sp)+,fr0 /initial guess | |
| 43 | mov $4,r0 | |
| 44 | 1: | |
| 45 | movf fr1,fr2 | |
| 46 | divf fr0,fr2 | |
| 47 | addf fr2,fr0 | |
| 48 | mulf $half,fr0 / x = (x+a/x)/2 | |
| 49 | sob r0,1b | |
| 50 | 2: | |
| 51 | movf (sp)+,fr2 | |
| 52 | movf (sp)+,fr1 | |
| 53 | ldfps (sp)+ | |
| 54 | mov (sp)+,r0 | |
| 55 | clc | |
| 56 | rts pc | |
| 57 | / | |
| 58 | half = 40000 |