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 * 8 * Redistribution and use in source and binary forms are permitted 9 * provided that the above copyright notice and this paragraph are 10 * duplicated in all such forms and that any documentation, 11 * advertising materials, and other materials related to such 12 * distribution and use acknowledge that the software was developed 13 * by the University of California, Berkeley. The name of the 14 * University may not be used to endorse or promote products derived 15 * from this software without specific prior written permission. 16 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 18 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. 19 */ 20 21#if defined(SYSLIBC_SCCS) && !defined(lint) 22 .asciz "@(#)mulf.s 1.2 (Berkeley) 02/17/89" 23#endif /* SYSLIBC_SCCS and not lint */ 24 25#include <tahoemath/fp.h> 26#include "DEFS.h" 27 28#define HIDDEN 23 /* here we count from 0 not from 1 as in fp.h */ 29 30XENTRY(mulf, R2|R3|R4|R5|R6|R7|R8|R9) 31 clrl r3 /* r3 - sign: 0 for positive,1 for negative. */ 32 movl 4(fp),r0 33 jgeq 1f 34 movl $1,r3 351: movl 12(fp),r2 36 jgeq 2f 37 bbc $0,r3,1f /* seconed operand is negative. */ 38 clrl r3 /* if first was negative, make result positive. */ 39 jmp 2f 401: movl $1,r3 /* if first was positive, make result negative. */ 412: andl2 $EXPMASK,r0 /* compute first 'pure'exponent. */ 42 jeql is_res1 43 shrl $EXPSHIFT,r0,r0 44 subl2 $BIASP1,r0 45 andl2 $EXPMASK,r2 /* compute seconed 'pure'exponent. */ 46 jeql is_res2 47 shrl $EXPSHIFT,r2,r2 48 subl2 $BIASP1,r2 49 addl2 r0,r2 /* add the exponents. */ 50 addl2 $(BIASP1+2),r2 51 jleq underflow 52 cmpl r2,$258 /* normalization can make the exp. smaller. */ 53 jgeq overflow 54 /* 55 * We have the sign in r3,the exponent in r2,now is the time to 56 * perform the multiplication... 57 */ 58 /* fetch first fraction: (r0) */ 59 andl3 $(0!(EXPMASK | SIGNBIT)),4(fp),r0 60 orl2 $(0!CLEARHID),r0 61 shll $7,r0,r0 /* leave the sign bit cleared. */ 62 63 /* fetch seconed fraction: (r4) */ 64 andl3 $(0!(EXPMASK | SIGNBIT)),12(fp),r4 65 orl2 $(0!CLEARHID),r4 66 shll $7,r4,r4 /* leave the sign bit cleared. */ 67 68 69 emul r4,r0,$0,r0 70 movl r0,r4 /* to see how much we realy need to shift. */ 71 movl $6,r5 /* r5 - shift counter. */ 72 shrl $7,r4,r4 /* dummy shift. */ 731: bbs $HIDDEN,r4,realshift 74 shll $1,r4,r4 75 decl r2 /* update exponent. */ 76 jeql underflow 77 decl r5 /* update shift counter. */ 78 jmp 1b 79realshift: 80 shrl r5,r0,r0 81 bbc $0,r1,shiftmore 82 incl r1 /* rounding. */ 83shiftmore: 84 shrl $1,r0,r0 85comb: 86 andl2 $CLEARHID,r0 87 shll $EXPSHIFT,r2,r4 88 orl2 r4,r0 89 cmpl r2,$256 90 jlss 1f 91 callf $4,sfpover 92sign: 931: bbc $0,r3,done 94 orl2 $SIGNBIT,r0 95done: ret 96 97 98 99is_res1: 100 bbc $31,4(fp),retzero 101 callf $4,sfpresop 102 ret 103is_res2: 104 bbc $31,12(fp),retzero 105 callf $4,sfpresop 106 ret 107 retzero: 108 clrl r0 109 ret 110 overflow: 111 callf $4,sfpover 112 jmp sign 113 underflow: 114 callf $4,sfpunder 115 ret 116 117 118 119