projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| a6730a00 | 1 | /* Kaddf.s 1.4 90/12/04 */ |
| 8eb02f2a | 2 | |
| a6730a00 | 3 | #include "../math/fp.h" |
| 9d1834ba | 4 | #include "../tahoe/SYS.h" |
| 8eb02f2a | 5 | |
| 2b252132 SL |
6 | /* |
| 7 | * _Kaddf(acc_most,acc_least,op_most,op_least,hfs) | |
| 8 | */ | |
| 8eb02f2a | 9 | .text |
| 2b252132 SL |
10 | ENTRY(Kaddf, R10|R9|R8|R7|R6|R5|R4|R3|R2) |
| 11 | /* | |
| 12 | * see which operand has a greater exponent | |
| 13 | * The greater one will be fetched into r0,r1,r2,r3. | |
| 14 | * r0,r1 - 'pure' fraction, r2 - exponent, r3 - sign). | |
| 15 | * The smaller operand will be fetched into r4,r5,r6,r7. | |
| 16 | */ | |
| 8eb02f2a SL |
17 | tstl 4(fp) # handle (a+b) where a and/or b = 0.0 |
| 18 | jneq next | |
| 19 | movl $0,r1 | |
| 20 | movl 12(fp),r0 | |
| 21 | ret | |
| 22 | next: | |
| 23 | tstl 12(fp) | |
| 24 | jneq doit | |
| 25 | movl $0,r1 | |
| 26 | movl 4(fp),r0 | |
| 27 | ret | |
| 28 | doit: | |
| 29 | andl3 $EXPMASK,4(fp),r0 | |
| 30 | andl3 $EXPMASK,12(fp),r1 | |
| 31 | cmpl r0,r1 | |
| 32 | jgtr first_greater | |
| 33 | ||
| 34 | movl 12(fp),r0 # bigger operand to r0,r1 | |
| 35 | movl 16(fp),r1 | |
| 36 | ||
| 37 | movl 4(fp),r4 # smaller operand to r4,r5 | |
| 38 | movl 8(fp),r5 | |
| 39 | jmp expo | |
| 40 | ||
| 41 | first_greater: | |
| 42 | movl 4(fp),r0 # bigger operand to r0,r1 | |
| 43 | movl 8(fp),r1 | |
| 44 | ||
| 45 | movl 12(fp),r4 # smaller operand to r4,r5 | |
| 46 | movl 16(fp),r5 | |
| 47 | ||
| 48 | ||
| 49 | # | |
| 50 | #compute exponents: | |
| 51 | # | |
| 52 | expo: | |
| 53 | andl3 $EXPMASK,r0,r2 # r2 will hold the exponent. | |
| 54 | shrl $EXPSHIFT,r2,r2 | |
| 55 | andl3 $EXPMASK,r4,r6 # r6 will hold the exponent. | |
| 56 | shrl $EXPSHIFT,r6,r6 | |
| 57 | # | |
| 58 | #compare the exponents: | |
| 59 | # | |
| 60 | subl3 r6,r2,r8 | |
| 61 | jeql signs | |
| 62 | cmpl r8,$MAX_EXP_DIF | |
| 63 | jlss signs | |
| 64 | ret # return the bigger number. | |
| 65 | ||
| 66 | # | |
| 67 | #remember the signs: | |
| 68 | # | |
| 69 | signs: | |
| 70 | clrl r3 | |
| 71 | bbc $31,r0,sign2 # if negative remember it. | |
| 72 | incl r3 | |
| 73 | sign2: | |
| 74 | clrl r7 | |
| 75 | bbc $31,r4,frac # if negative remember it. | |
| 76 | incl r7 | |
| 77 | # | |
| 78 | #compute 'pure' fraction: | |
| 79 | # | |
| 80 | frac: | |
| 81 | # clear the non fraction parts. | |
| 82 | andl2 $(0!(EXPMASK | SIGNBIT)),r0 | |
| 83 | # add the hidden bit. | |
| 84 | orl2 $(0!CLEARHID),r0 | |
| 85 | # clear the non fraction parts. | |
| 86 | andl2 $(0!(EXPMASK | SIGNBIT)),r4 | |
| 87 | # add the hidden bit. | |
| 88 | orl2 $(0!CLEARHID),r4 | |
| 89 | ||
| 90 | # | |
| 91 | #shift the smaller operand: | |
| 92 | # | |
| 93 | shrq r8,r4,r4 | |
| 94 | eql_exps: | |
| 95 | cmpl r3,r7 | |
| 96 | jeql add | |
| 97 | bbc $0,r3,negr4r5 | |
| 98 | # | |
| 99 | #negate the pair r0,r1: | |
| 100 | # | |
| 101 | clrl r3 | |
| 102 | mcoml r1,r1 | |
| 103 | clrl r9 # r9 - carry flag. | |
| 104 | incl r1 | |
| 105 | bcc comr0 | |
| 106 | incl r9 # remember the carry. | |
| 107 | comr0: mcoml r0,r0 | |
| 108 | bbc $0,r9,add | |
| 109 | incl r0 | |
| 110 | ||
| 111 | # | |
| 112 | #add the fractions: | |
| 113 | # | |
| 114 | add: | |
| 115 | clrl r10 # to remember the sign of the result. | |
| 116 | addl2 r5,r1 | |
| 117 | adwc r4,r0 | |
| 118 | jgeq norm # if positive go to normelize. | |
| 119 | incl r10 # else remember it and negate the result. | |
| 120 | # | |
| 121 | #negate the pair r0,r1: | |
| 122 | # | |
| 123 | clrl r3 | |
| 124 | mcoml r1,r1 | |
| 125 | clrl r9 # r9 - carry flag. | |
| 126 | incl r1 | |
| 127 | bcc comr00 | |
| 128 | incl r9 # remember the carry. | |
| 129 | comr00: mcoml r0,r0 | |
| 130 | bbc $0,r9,norm | |
| 131 | incl r0 | |
| 132 | norm: pushl 20(fp) # addr of returnen exception. | |
| 2b252132 | 133 | callf $8,_Kfnorm |
| 8eb02f2a SL |
134 | |
| 135 | # | |
| 136 | #add the sign bit | |
| 137 | # | |
| 138 | bbs $0,r10,negative | |
| 139 | bbs $0,r3,negative | |
| 140 | ret | |
| 141 | negative: | |
| 142 | orl2 $SIGNBIT,r0 | |
| 143 | ret | |
| 144 | ||
| 145 | ||
| 146 | # | |
| 147 | #negate the pair r4,r5: | |
| 148 | # | |
| 149 | negr4r5: | |
| 150 | clrl r7 | |
| 151 | mcoml r5,r5 | |
| 152 | clrl r9 # r9 - carry flag. | |
| 153 | incl r5 | |
| 154 | bcc comr4 | |
| 155 | incl r9 # remember the carry. | |
| 156 | comr4: mcoml r4,r4 | |
| 157 | bbc $0,r9,add | |
| 158 | incl r4 | |
| 159 | jmp add | |
| 160 | ||
| 161 | ||
| 162 | movl r4,r0 # return the smaller operand. | |
| 163 | movl r5,r1 | |
| 164 | ret | |
| 165 |