1/*- 2 * Copyright (c) 1985 The 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 * %sccs.include.redist.c% 9 * 10 * @(#)Kdivf.s 7.1 (Berkeley) 12/06/90 11 */ 12 13#include "../math/fp.h" 14#include "../math/Kfp.h" 15#include "../tahoe/SYS.h" 16 17#define HIDDEN 23 # here we count from 0 not from 1 as in fp.h 18 19 .text 20ENTRY(Kdivf, R9|R8|R7|R6|R5|R4|R3|R2) 21 clrl r1 22 clrl r3 # r3 - sign: 0 for positive,1 for negative. 23 movl 4(fp),r0 24 jgeq 1f 25 movl $1,r3 261: movl 12(fp),r2 27 jgeq 2f 28 bbc $0,r3,1f # seconed operand is negative. 29 clrl r3 # if first was negative, make result positive. 30 jmp 2f 311: movl $1,r3 # if first was positive, make result negative. 322: andl2 $EXPMASK,r0 # compute first 'pure'exponent. 33 jeql retz 34 shrl $EXPSHIFT,r0,r0 35 subl2 $BIAS,r0 36 andl2 $EXPMASK,r2 # compute seconed 'pure'exponent. 37 jeql retz2 38 shrl $EXPSHIFT,r2,r2 39 subl2 $BIAS,r2 40 subl3 r2,r0,r2 # subtruct the exponents. 41 addl2 $BIAS,r2 42 jleq underf 43 # normalization can make the exp. smaller. 44 # 45 # We have the sign in r3,the exponent in r2,now is the time to 46 # perform the division... 47 # 48 # fetch dividend. (r0) 49 andl3 $(0!(EXPMASK | SIGNBIT)),4(fp),r0 50 orl2 $(0!CLEARHID),r0 51 clrl r1 52 53 # fetch divisor : (r6) 54 andl3 $(0!(EXPMASK | SIGNBIT)),12(fp),r6 55 orl2 $(0!CLEARHID),r6 56 57 shll $2,r6,r6 # make the divisor bigger so we will not 58 # get overflow at the divission. 59 ediv r6,r0,r0,r7 # quo to r0, rem to r7 60 subl2 $6,r2 # to compensate for: normalization (-24), 61 # ediv (+32), shifting r6 (-2). 62 63over: 64 pushl 20(fp) 65 callf $8,_Kfnorm # we can use fnorm because we have data 66 # at r1 as well.(sfnorm takes care only 67 # of r0). 68sign: 691: bbc $0,r3,done 70 orl2 $SIGNBIT,r0 71done: ret 72 73retz: 74 clrl r0 75 ret 76 77retz2: bbc $31,12(fp),z_div 78 clrl r0 79 ret 80 81underf: 82 orl2 $HFS_UNDF,*20(fp) 83 ret 84z_div: 85 orl2 $HFS_DIVZ,*20(fp) 86 ret 87