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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 | * | |
| 019bea33 | 8 | * %sccs.include.redist.c% |
| 1f0502d3 KB |
9 | */ |
| 10 | ||
| 11 | #if defined(SYSLIBC_SCCS) && !defined(lint) | |
| 019bea33 | 12 | .asciz "@(#)addd.s 1.3 (Berkeley) %G%" |
| 1f0502d3 | 13 | #endif /* SYSLIBC_SCCS and not lint */ |
| 5733b822 SL |
14 | |
| 15 | #include <tahoemath/fp.h> | |
| 16 | #include "DEFS.h" | |
| 17 | ||
| 18 | XENTRY(addd, R2|R3|R4|R5|R6|R7|R8|R9|R10) | |
| 19 | /* | |
| 20 | * see which operand has a greater exponent | |
| 21 | * The greater one will be fetched into r0,r1,r2,r3. | |
| 22 | * r0,r1 - 'pure' fraction, r2 - exponent, r3 - sign). | |
| 23 | * The smaller operand will be fetched into r4,r5,r6,r7. | |
| 24 | */ | |
| 25 | andl3 $EXPMASK,4(fp),r0 | |
| 26 | andl3 $EXPMASK,12(fp),r1 | |
| 27 | cmpl r0,r1 | |
| 28 | jgtr first_greater | |
| 29 | ||
| 30 | movl 12(fp),r0 # bigger operand to r0,r1 | |
| 31 | movl 16(fp),r1 | |
| 32 | ||
| 33 | movl 4(fp),r4 # smaller operand to r4,r5 | |
| 34 | movl 8(fp),r5 | |
| 35 | jmp expo | |
| 36 | ||
| 37 | first_greater: | |
| 38 | movl 4(fp),r0 # bigger operand to r0,r1 | |
| 39 | movl 8(fp),r1 | |
| 40 | ||
| 41 | movl 12(fp),r4 # smaller operand to r4,r5 | |
| 42 | movl 16(fp),r5 | |
| 43 | ||
| 44 | /* | |
| 45 | * compute exponents: | |
| 46 | */ | |
| 47 | expo: | |
| 48 | andl3 $EXPMASK,r0,r2 # r2 will hold the exponent. | |
| 49 | jeql is_res1 # check for reserved operand. | |
| 50 | shrl $EXPSHIFT,r2,r2 | |
| 51 | ||
| 52 | ||
| 53 | andl3 $EXPMASK,r4,r6 # r6 will hold the exponent. | |
| 54 | jeql is_res2 # check for reserved operand. | |
| 55 | shrl $EXPSHIFT,r6,r6 | |
| 56 | /* | |
| 57 | * compare the exponents: | |
| 58 | */ | |
| 59 | subl3 r6,r2,r8 | |
| 60 | jeql signs | |
| 61 | cmpl r8,$MAX_EXP_DIF | |
| 62 | jlss signs | |
| 63 | ret # return the bigger number. | |
| 64 | ||
| 65 | /* | |
| 66 | * remember the signs: | |
| 67 | */ | |
| 68 | signs: | |
| 69 | clrl r3 | |
| 70 | bbc $31,r0,sign2 # if negative remember it. | |
| 71 | incl r3 | |
| 72 | sign2: | |
| 73 | clrl r7 | |
| 74 | bbc $31,r4,frac # if negative remember it. | |
| 75 | incl r7 | |
| 76 | /* | |
| 77 | * compute 'pure' fraction: | |
| 78 | */ | |
| 79 | frac: | |
| 80 | # clear the non fraction parts. | |
| 81 | andl2 $(0!(EXPMASK | SIGNBIT)),r0 | |
| 82 | # add the hidden bit. | |
| 83 | orl2 $(0!CLEARHID),r0 | |
| 84 | # clear the non fraction parts. | |
| 85 | andl2 $(0!(EXPMASK | SIGNBIT)),r4 | |
| 86 | # add the hidden bit. | |
| 87 | orl2 $(0!CLEARHID),r4 | |
| 88 | ||
| 89 | /* | |
| 90 | * shift the smaller operand: | |
| 91 | */ | |
| 92 | shrq r8,r4,r4 | |
| 93 | eql_exps: | |
| 94 | cmpl r3,r7 | |
| 95 | jeql add | |
| 96 | bbc $0,r3,negr4r5 | |
| 97 | /* | |
| 98 | * negate the pair r0,r1: | |
| 99 | */ | |
| 100 | clrl r3 | |
| 101 | mcoml r1,r1 | |
| 102 | clrl r9 # r9 - carry flag. | |
| 103 | incl r1 | |
| 104 | bcc comr0 | |
| 105 | incl r9 # remember the carry. | |
| 106 | comr0: mcoml r0,r0 | |
| 107 | bbc $0,r9,add | |
| 108 | incl r0 | |
| 109 | ||
| 110 | /* | |
| 111 | * add the fractions: | |
| 112 | */ | |
| 113 | add: | |
| 114 | clrl r10 # to remember the sign of the result. | |
| 115 | addl2 r5,r1 | |
| 116 | adwc r4,r0 | |
| 117 | jgeq norm # if positive go to normelize. | |
| 118 | incl r10 # else remember it and negate the result. | |
| 119 | /* | |
| 120 | * negate the pair r0,r1: | |
| 121 | */ | |
| 122 | clrl r3 | |
| 123 | mcoml r1,r1 | |
| 124 | clrl r9 # r9 - carry flag. | |
| 125 | incl r1 | |
| 126 | bcc comr00 | |
| 127 | incl r9 # remember the carry. | |
| 128 | comr00: mcoml r0,r0 | |
| 129 | bbc $0,r9,norm | |
| 130 | incl r0 | |
| 131 | norm: callf $4,fnorm | |
| 132 | ||
| 133 | /* | |
| 134 | * add the sign bit | |
| 135 | */ | |
| 136 | bbs $0,r10,negative | |
| 137 | bbs $0,r3,negative | |
| 138 | ret | |
| 139 | negative: | |
| 140 | orl2 $SIGNBIT,r0 | |
| 141 | ret | |
| 142 | ||
| 143 | ||
| 144 | /* | |
| 145 | * negate the pair r4,r5: | |
| 146 | */ | |
| 147 | negr4r5: | |
| 148 | clrl r7 | |
| 149 | mcoml r5,r5 | |
| 150 | clrl r9 # r9 - carry flag. | |
| 151 | incl r5 | |
| 152 | bcc comr4 | |
| 153 | incl r9 # remember the carry. | |
| 154 | comr4: mcoml r4,r4 | |
| 155 | bbc $0,r9,add | |
| 156 | incl r4 | |
| 157 | jmp add | |
| 158 | ||
| 159 | ||
| 160 | is_res1: | |
| 161 | bbs $31,r0,res_op | |
| 162 | movl r4,r0 # return the smaller operand. | |
| 163 | movl r5,r1 | |
| 164 | ret | |
| 165 | ||
| 166 | is_res2: | |
| 167 | bbs $31,r4,res_op | |
| 168 | ret # we allready have the 'result' in r0,r1. | |
| 169 | ||
| 170 | res_op: | |
| 171 | callf $4,fpresop | |
| 172 | ret |