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 "@(#)divd.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(divd, 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 $BIAS,r0 45 andl2 $EXPMASK,r2 # compute seconed 'pure'exponent. 46 jeql is_res2 47 shrl $EXPSHIFT,r2,r2 48 subl2 $BIAS,r2 49 subl3 r2,r0,r2 # subtruct the exponents. 50 addl2 $BIAS,r2 51 jleq underf 52 # normalization can make the exp. smaller. 53 # 54 # We have the sign in r3,the exponent in r2,now is the time to 55 # perform the division... 56 # 57 # fetch dividend. (r4,r5) 58 andl3 $(0!(EXPMASK | SIGNBIT)),4(fp),r4 59 orl2 $(0!CLEARHID),r4 60 movl 8(fp),r5 61 62 # fetch divisor : (r6,r7) 63 andl3 $(0!(EXPMASK | SIGNBIT)),12(fp),r6 64 orl2 $(0!CLEARHID),r6 65 movl 16(fp),r7 66 67 movl $0,r0 # init r0,r1 to be zeros 68 movl $0,r1 69 movl $(0!CLEARHID),r8# r8 first bit to set (if). 70 shll $1,r8,r8 # to have one more bit,because we might 71 # have to shift left to normelize. 72 movl $0,r9 73 742: 75 subl2 r7,r5 76 sbwc r6,r4 77 jgeq 1f 78 addl2 r7,r5 79 adwc r6,r4 80 shlq $1,r4,r4 81 shrq $1,r8,r8 82 jeql over 83 jmp 2b 841: 85 orl2 r8,r0 86 orl2 r9,r1 87 shlq $1,r4,r4 88 shrq $1,r8,r8 89 jneq 2b 90 91over: 92 callf $4,fnorm 93sign: 941: bbc $0,r3,done 95 orl2 $SIGNBIT,r0 96done: ret 97 98is_res1: 99 bbc $31,4(fp),retz 100 callf $4,fpresop 101 ret 102is_res2: 103 bbc $31,12(fp),z_div 104 callf $4,fpresop 105 ret 106retz: 107 clrl r0 108 clrl r1 109 ret 110underf: 111 callf $4,fpunder 112 ret 113z_div: 114 callf $4,fpzdiv 115 ret 116