projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 6ed22137 | 1 | #ifdef LIBC_SCCS |
| c338853c | 2 | .asciz "@(#)modf.s 1.2 (Berkeley) %G%" |
| 6ed22137 SL |
3 | #endif LIBC_SCCS |
| 4 | ||
| 5 | /* | |
| 6 | * double modf (value, iptr) | |
| 7 | * double value, *iptr; | |
| 8 | * | |
| 9 | * Modf returns the fractional part of "value", | |
| 10 | * and stores the integer part indirectly through "iptr". | |
| 11 | * | |
| 12 | * This version uses floating point (look in ../fpe for | |
| 13 | * a much slower integer version). | |
| 14 | */ | |
| 15 | ||
| 16 | #include "DEFS.h" | |
| 17 | ||
| 18 | ENTRY(modf, 0) | |
| c338853c SL |
19 | ldd 4(fp) # value |
| 20 | cvdl r2 # integerize | |
| 21 | bvs 1f # did integer part overflow? | |
| 22 | cvld r2 # integer part | |
| 23 | std r0 | |
| 24 | std *12(fp) # *iptr = r2 | |
| 6ed22137 | 25 | ldd 4(fp) |
| c338853c SL |
26 | subd r0 # value-(int)value |
| 27 | std r0 # return fraction | |
| 6ed22137 SL |
28 | ret |
| 29 | 1: | |
| c338853c SL |
30 | /* |
| 31 | * If the integer portion overflowed, mask out the fractional | |
| 32 | * bits in the double word instead of cvdl-ing. | |
| 33 | */ | |
| 34 | ldd 4(fp) | |
| 35 | std r0 # (r0,r1) = value | |
| 36 | shrl $23,r0,r2 # extract sign,exponent of value | |
| 37 | andl2 $255,r2 # exponent | |
| 38 | subl2 $152,r2 # e-152 | |
| 39 | /* | |
| 40 | * If it overflowed then value>=2^31 and e>=160 | |
| 41 | * so we mask only r1 (low bits of fraction), not r0 | |
| 42 | */ | |
| 43 | mnegl $1,r3 | |
| 44 | shrl r2,r3,r3 # -1>>(e-152) is neg mask to clear fraction | |
| 45 | mcoml r3,r3 # complement mask | |
| 46 | andl2 r3,r1 # mask off truly fractional bits from fraction | |
| 47 | ldd r0 # now (r0,r1) = integerized value | |
| 48 | std *12(fp) # *iptr = integerized | |
| 6ed22137 SL |
49 | ldd 4(fp) |
| 50 | subd r0 | |
| c338853c | 51 | std r0 # return fraction |
| 6ed22137 | 52 | ret |