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| Commit | Line | Data |
|---|---|---|
| a6730a00 | 1 | /* Kmulf.s 1.4 90/12/04 */ |
| 5245a337 | 2 | |
| a6730a00 KB |
3 | #include "../math/fp.h" |
| 4 | #include "../math/Kfp.h" | |
| 9d1834ba | 5 | #include "../tahoe/SYS.h" |
| 5245a337 | 6 | |
| 2b252132 | 7 | #define HIDDEN 23 /* here we count from 0 not from 1 as in fp.h */ |
| 5245a337 | 8 | |
| 2b252132 SL |
9 | /* |
| 10 | * _Kmulf(acc_most,acc_least,op_most,op_least,hfs) | |
| 11 | */ | |
| 5245a337 | 12 | .text |
| 2b252132 | 13 | ENTRY(Kmulf, R5|R4|R3|R2) |
| 5245a337 SL |
14 | clrl r3 /* r3 - sign: 0 for positive,1 for negative. */ |
| 15 | movl 4(fp),r0 | |
| 16 | jgeq 1f | |
| 17 | movl $1,r3 | |
| 18 | 1: 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 | |
| 23 | 1: movl $1,r3 /* if first was positive, make result negative. */ | |
| 24 | 2: 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. */ | |
| 56 | 1: 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 | |
| 62 | realshift: | |
| 63 | shrl r5,r0,r0 | |
| 64 | bbc $0,r1,shiftmore | |
| 65 | incl r1 /* rounding. */ | |
| 66 | shiftmore: | |
| 67 | shrl $1,r0,r0 | |
| 68 | comb: | |
| 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) | |
| 75 | sign: | |
| 76 | 1: bbc $0,r3,done | |
| 77 | orl2 $SIGNBIT,r0 | |
| 78 | done: 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 |