projects / unix-history / blame
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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 | * | |
| c0567266 KB |
8 | * Redistribution and use in source and binary forms, with or without |
| 9 | * modification, are permitted provided that the following conditions | |
| 10 | * are met: | |
| 11 | * 1. Redistributions of source code must retain the above copyright | |
| 12 | * notice, this list of conditions and the following disclaimer. | |
| 13 | * 2. Redistributions in binary form must reproduce the above copyright | |
| 14 | * notice, this list of conditions and the following disclaimer in the | |
| 15 | * documentation and/or other materials provided with the distribution. | |
| 16 | * 3. All advertising materials mentioning features or use of this software | |
| 17 | * must display the following acknowledgement: | |
| 18 | * This product includes software developed by the University of | |
| 19 | * California, Berkeley and its contributors. | |
| 20 | * 4. Neither the name of the University nor the names of its contributors | |
| 21 | * may be used to endorse or promote products derived from this software | |
| 22 | * without specific prior written permission. | |
| 23 | * | |
| 24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
| 25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| 26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
| 27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
| 28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
| 29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
| 30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
| 31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
| 32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
| 33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
| 34 | * SUCH DAMAGE. | |
| 1f0502d3 KB |
35 | */ |
| 36 | ||
| 37 | #if defined(SYSLIBC_SCCS) && !defined(lint) | |
| 1c15e888 | 38 | .asciz "@(#)sfnorm.s 1.3 (Berkeley) 6/1/90" |
| 1f0502d3 | 39 | #endif /* SYSLIBC_SCCS and not lint */ |
| b9f214cf SL |
40 | |
| 41 | #include <tahoemath/fp.h> | |
| 42 | #include "DEFS.h" | |
| 43 | ||
| 44 | XENTRY(sfnorm, R2|R3|R4|R5|R6) | |
| 45 | clrl r1 | |
| 46 | movl r0,r4 /* copy to temporary. */ | |
| 47 | jeql retzero | |
| 48 | clrl r3 /* r3 - pos of m.s.b */ | |
| 49 | inr00: ffs r4,r6 | |
| 50 | incl r6 | |
| 51 | addl2 r6,r3 | |
| 52 | shrl r6,r4,r4 | |
| 53 | jneq inr00 | |
| 54 | ||
| 55 | cmpshift: | |
| 56 | /* compute the shift (r4). */ | |
| 57 | subl3 r3,$HID_POS,r4 | |
| 58 | jlss shiftr /* if less then zero we shift right. */ | |
| 59 | shll r4,r0,r0 /* else we shift left. */ | |
| 60 | subl2 r4,r2 /* uodate exponent. */ | |
| 61 | jleq underflow /* if less then 0 (biased) it is underflow. */ | |
| 62 | jmp combine /* go to combine exponent and fraction. */ | |
| 63 | shiftr: | |
| 64 | mnegl r4,r4 | |
| 65 | shrl r4,r0,r0 /* shift right. */ | |
| 66 | addl2 r4,r2 /* update exponent */ | |
| 67 | cmpl r2,$256 | |
| 68 | jgeq overflow /* check for overflow. */ | |
| 69 | combine: | |
| 70 | andl2 $CLEARHID,r0 /* clear the hidden bit. */ | |
| 71 | shal $EXPSHIFT,r2,r2 /* shift the exponent to its proper place. */ | |
| 72 | orl2 r2,r0 | |
| 73 | ret | |
| 74 | ||
| 75 | underflow: | |
| 76 | callf $4,sfpunder | |
| 77 | ret | |
| 78 | ||
| 79 | overflow: | |
| 80 | callf $4,sfpover | |
| 81 | ret | |
| 82 | retzero: | |
| 83 | clrl r0 | |
| 84 | ret |