projects / unix-history / blame
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|---|---|---|
| 1f0502d3 KB |
1 | /* |
| 2 | * Copyright (c) 1986 Regents of the University of California. | |
| 3 | * All rights reserved. | |
| 4 | * | |
| 5 | * This code is derived from software contributed to Berkeley by | |
| 6 | * Computer Consoles Inc. | |
| 7 | * | |
| 019bea33 | 8 | * %sccs.include.redist.c% |
| 1f0502d3 KB |
9 | */ |
| 10 | ||
| 11 | #if defined(SYSLIBC_SCCS) && !defined(lint) | |
| 019bea33 | 12 | .asciz "@(#)sfnorm.s 1.3 (Berkeley) %G%" |
| 1f0502d3 | 13 | #endif /* SYSLIBC_SCCS and not lint */ |
| b9f214cf SL |
14 | |
| 15 | #include <tahoemath/fp.h> | |
| 16 | #include "DEFS.h" | |
| 17 | ||
| 18 | XENTRY(sfnorm, R2|R3|R4|R5|R6) | |
| 19 | clrl r1 | |
| 20 | movl r0,r4 /* copy to temporary. */ | |
| 21 | jeql retzero | |
| 22 | clrl r3 /* r3 - pos of m.s.b */ | |
| 23 | inr00: ffs r4,r6 | |
| 24 | incl r6 | |
| 25 | addl2 r6,r3 | |
| 26 | shrl r6,r4,r4 | |
| 27 | jneq inr00 | |
| 28 | ||
| 29 | cmpshift: | |
| 30 | /* compute the shift (r4). */ | |
| 31 | subl3 r3,$HID_POS,r4 | |
| 32 | jlss shiftr /* if less then zero we shift right. */ | |
| 33 | shll r4,r0,r0 /* else we shift left. */ | |
| 34 | subl2 r4,r2 /* uodate exponent. */ | |
| 35 | jleq underflow /* if less then 0 (biased) it is underflow. */ | |
| 36 | jmp combine /* go to combine exponent and fraction. */ | |
| 37 | shiftr: | |
| 38 | mnegl r4,r4 | |
| 39 | shrl r4,r0,r0 /* shift right. */ | |
| 40 | addl2 r4,r2 /* update exponent */ | |
| 41 | cmpl r2,$256 | |
| 42 | jgeq overflow /* check for overflow. */ | |
| 43 | combine: | |
| 44 | andl2 $CLEARHID,r0 /* clear the hidden bit. */ | |
| 45 | shal $EXPSHIFT,r2,r2 /* shift the exponent to its proper place. */ | |
| 46 | orl2 r2,r0 | |
| 47 | ret | |
| 48 | ||
| 49 | underflow: | |
| 50 | callf $4,sfpunder | |
| 51 | ret | |
| 52 | ||
| 53 | overflow: | |
| 54 | callf $4,sfpover | |
| 55 | ret | |
| 56 | retzero: | |
| 57 | clrl r0 | |
| 58 | ret |