projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| a6730a00 | 1 | /* Ksfnorm.s 1.4 90/12/04 */ |
| 5245a337 | 2 | |
| a6730a00 KB |
3 | #include "../math/fp.h" |
| 4 | #include "../math/Kfp.h" | |
| 9d1834ba | 5 | #include "../tahoe/SYS.h" |
| 5245a337 | 6 | |
| 2b252132 SL |
7 | /* |
| 8 | * Ksfnorm(hfs) | |
| 9 | */ | |
| 5245a337 | 10 | .text |
| 2b252132 | 11 | ENTRY(Ksfnorm, R6|R5|R4|R3|R2) |
| 5245a337 SL |
12 | clrl r1 |
| 13 | movl r0,r4 /* copy to temporary. */ | |
| 14 | jeql retzero | |
| 15 | clrl r3 /* r3 - pos of m.s.b */ | |
| 16 | inr00: ffs r4,r6 | |
| 17 | incl r6 | |
| 18 | addl2 r6,r3 | |
| 19 | shrl r6,r4,r4 | |
| 20 | jneq inr00 | |
| 21 | ||
| 22 | cmpshift: | |
| 23 | /* compute the shift (r4). */ | |
| 24 | subl3 r3,$HID_POS,r4 | |
| 25 | jlss shiftr /* if less then zero we shift right. */ | |
| 26 | shll r4,r0,r0 /* else we shift left. */ | |
| 27 | subl2 r4,r2 /* uodate exponent. */ | |
| 28 | jleq underflow /* if less then 0 (biased) it is underflow. */ | |
| 29 | jmp combine /* go to combine exponent and fraction. */ | |
| 30 | shiftr: | |
| 31 | mnegl r4,r4 | |
| 32 | shrl r4,r0,r0 /* shift right. */ | |
| 33 | addl2 r4,r2 /* update exponent */ | |
| 34 | cmpl r2,$256 | |
| 35 | jgeq overflow /* check for overflow. */ | |
| 36 | combine: | |
| 37 | andl2 $CLEARHID,r0 /* clear the hidden bit. */ | |
| 38 | shal $EXPSHIFT,r2,r2 /* shift the exponent to its proper place. */ | |
| 39 | orl2 r2,r0 | |
| 40 | ret | |
| 41 | ||
| 42 | underflow: | |
| 43 | orl2 $HFS_UNDF,*4(fp) | |
| 44 | ret | |
| 45 | ||
| 46 | overflow: | |
| 47 | orl2 $HFS_OVF,*4(fp) | |
| 48 | ret | |
| 49 | retzero: | |
| 50 | clrl r0 | |
| 51 | ret |