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 | * | |
| 1c15e888 C |
8 | * Redistribution and use in source and binary forms are permitted |
| 9 | * provided that: (1) source distributions retain this entire copyright | |
| 10 | * notice and comment, and (2) distributions including binaries display | |
| 11 | * the following acknowledgement: ``This product includes software | |
| 12 | * developed by the University of California, Berkeley and its contributors'' | |
| 13 | * in the documentation or other materials provided with the distribution | |
| 14 | * and in all advertising materials mentioning features or use of this | |
| 15 | * software. Neither the name of the University nor the names of its | |
| 16 | * contributors may be used to endorse or promote products derived | |
| 17 | * from this software without specific prior written permission. | |
| 18 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR | |
| 19 | * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED | |
| 20 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. | |
| 1f0502d3 KB |
21 | */ |
| 22 | ||
| 23 | #if defined(SYSLIBC_SCCS) && !defined(lint) | |
| 1c15e888 | 24 | .asciz "@(#)cvtud.s 1.3 (Berkeley) 6/1/90" |
| 1f0502d3 | 25 | #endif /* SYSLIBC_SCCS and not lint */ |
| 0eecbc43 SL |
26 | |
| 27 | #include <tahoemath/fp.h> | |
| 28 | #include "DEFS.h" | |
| 29 | ||
| 30 | XENTRY(cvtud, R2|R3|R4|R5) | |
| 31 | # | |
| 32 | # Some initializations: | |
| 33 | # | |
| 34 | clrl r2 # r2 - exponent. | |
| 35 | movl 4(fp),r0 # fetch operand. | |
| 36 | jeql retzero # return zero. | |
| 37 | # | |
| 38 | # Compute exponent: | |
| 39 | # | |
| 40 | positive: | |
| 41 | ffs r0,r1 | |
| 42 | incl r1 | |
| 43 | addl2 r1,r2 | |
| 44 | shrl r1,r0,r0 | |
| 45 | jneq positive # look for more set bits. | |
| 46 | # | |
| 47 | # we have the exponent in r2. | |
| 48 | # | |
| 49 | movl 4(fp),r0 # r0,r1 will hold the resulting f.p. number. | |
| 50 | clrl r1 | |
| 51 | # | |
| 52 | # Shift the fraction part to its proper place: | |
| 53 | # | |
| 54 | subl3 r2,$HID_POS,r3 | |
| 55 | jlss shiftr # if less then zero we have to shift right. | |
| 56 | shll r3,r0,r0 # else we shift left. | |
| 57 | jmp shifted | |
| 58 | shiftr: | |
| 59 | mnegl r3,r3 | |
| 60 | shrq r3,r0,r0 | |
| 61 | shifted: | |
| 62 | andl2 $CLEARHID,r0 # clear the hidden bit. | |
| 63 | shal $EXPSHIFT,r2,r2 # shift the exponent to its proper place. | |
| 64 | orl2 $EXPSIGN,r2 # set the exponent sign bit(to bias it). | |
| 65 | orl2 r2,r0 # combine exponent & fraction. | |
| 66 | sign_ok: | |
| 67 | ret | |
| 68 | ||
| 69 | retzero: | |
| 70 | clrl r0 | |
| 71 | clrl r1 | |
| 72 | ret | |
| 73 | ||
| 74 |