1/* Kmulf.s 1.2 86/01/03 */ 2 3#include "fp.h" 4#include "Kfp.h" 5#include "SYS.h" 6 7#define HIDDEN 23 /* here we count from 0 not from 1 as in fp.h */ 8 9/* 10 * _Kmulf(acc_most,acc_least,op_most,op_least,hfs) 11 */ 12 .text 13ENTRY(Kmulf, R5|R4|R3|R2) 14 clrl r3 /* r3 - sign: 0 for positive,1 for negative. */ 15 movl 4(fp),r0 16 jgeq 1f 17 movl $1,r3 181: movl 12(fp),r2 19 jgeq 2f 20 bbc $0,r3,1f /* seconed operand is negative. */ 21 clrl r3 /* if first was negative, make result positive. */ 22 jmp 2f 231: movl $1,r3 /* if first was positive, make result negative. */ 242: andl2 $EXPMASK,r0 /* compute first 'pure'exponent. */ 25 jeql retzero 26 shrl $EXPSHIFT,r0,r0 27 subl2 $BIASP1,r0 28 andl2 $EXPMASK,r2 /* compute seconed 'pure'exponent. */ 29 jeql retzero 30 shrl $EXPSHIFT,r2,r2 31 subl2 $BIASP1,r2 32 addl2 r0,r2 /* add the exponents. */ 33 addl2 $(BIASP1+2),r2 34 jleq underflow 35 cmpl r2,$258 /* normalization can make the exp. smaller. */ 36 jgeq overflow 37 /* 38 * We have the sign in r3,the exponent in r2,now is the time to 39 * perform the multiplication... 40 */ 41 /* fetch first fraction: (r0) */ 42 andl3 $(0!(EXPMASK | SIGNBIT)),4(fp),r0 43 orl2 $(0!CLEARHID),r0 44 shll $7,r0,r0 /* leave the sign bit cleared. */ 45 46 /* fetch seconed fraction: (r4) */ 47 andl3 $(0!(EXPMASK | SIGNBIT)),12(fp),r4 48 orl2 $(0!CLEARHID),r4 49 shll $7,r4,r4 /* leave the sign bit cleared. */ 50 51 52 emul r4,r0,$0,r0 53 movl r0,r4 /* to see how much we realy need to shift. */ 54 movl $6,r5 /* r5 - shift counter. */ 55 shrl $7,r4,r4 /* dummy shift. */ 561: bbs $HIDDEN,r4,realshift 57 shll $1,r4,r4 58 decl r2 /* update exponent. */ 59 jeql underflow 60 decl r5 /* update shift counter. */ 61 jmp 1b 62realshift: 63 shrl r5,r0,r0 64 bbc $0,r1,shiftmore 65 incl r1 /* rounding. */ 66shiftmore: 67 shrl $1,r0,r0 68comb: 69 andl2 $CLEARHID,r0 70 shll $EXPSHIFT,r2,r4 71 orl2 r4,r0 72 cmpl r2,$256 73 jlss 1f 74 orl2 $HFS_OVF,*20(fp) 75sign: 761: bbc $0,r3,done 77 orl2 $SIGNBIT,r0 78done: ret 79 80 81 82 retzero: 83 clrl r0 84 ret 85 overflow: 86 orl2 $HFS_OVF,*20(fp) 87 jmp sign 88 underflow: 89 orl2 $HFS_UNDF,*20(fp) 90 ret 91 92 93 94