projects / unix-history / blame
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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 | * | |
| 1c15e888 C |
8 | * Redistribution and use in source and binary forms are permitted |
| 9 | * provided that: (1) source distributions retain this entire copyright | |
| 10 | * notice and comment, and (2) distributions including binaries display | |
| 11 | * the following acknowledgement: ``This product includes software | |
| 12 | * developed by the University of California, Berkeley and its contributors'' | |
| 13 | * in the documentation or other materials provided with the distribution | |
| 14 | * and in all advertising materials mentioning features or use of this | |
| 15 | * software. Neither the name of the University nor the names of its | |
| 16 | * contributors may be used to endorse or promote products derived | |
| 17 | * from this software without specific prior written permission. | |
| 18 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR | |
| 19 | * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED | |
| 20 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. | |
| 1f0502d3 KB |
21 | */ |
| 22 | ||
| 23 | #if defined(SYSLIBC_SCCS) && !defined(lint) | |
| 1c15e888 | 24 | .asciz "@(#)addf.s 1.3 (Berkeley) 6/1/90" |
| 1f0502d3 | 25 | #endif /* SYSLIBC_SCCS and not lint */ |
| 5733b822 SL |
26 | |
| 27 | #include <tahoemath//fp.h> | |
| 28 | #include "DEFS.h" | |
| 29 | ||
| 30 | XENTRY(addf, R2|R3|R4|R5|R6|R7|R8|R9|R10) | |
| 31 | /* | |
| 32 | * see which operand has a greater exponent | |
| 33 | * The greater one will be fetched into r0,r2,r3. | |
| 34 | * r0- 'pure' fraction, r2 - exponent, r3 - sign). | |
| 35 | * The smaller operand will be fetched into r4,r6,r7. | |
| 36 | */ | |
| 37 | clrl r1 | |
| 38 | andl3 $EXPMASK,4(fp),r0 | |
| 39 | andl3 $EXPMASK,12(fp),r1 | |
| 40 | cmpl r0,r1 | |
| 41 | jgtr first_greater | |
| 42 | ||
| 43 | movl 12(fp),r0 # bigger operand to r0 | |
| 44 | ||
| 45 | movl 4(fp),r4 # smaller operand to r4 | |
| 46 | jmp expo | |
| 47 | ||
| 48 | first_greater: | |
| 49 | movl 4(fp),r0 # bigger operand to r0 | |
| 50 | ||
| 51 | movl 12(fp),r4 # smaller operand to r4 | |
| 52 | ||
| 53 | ||
| 54 | /* | |
| 55 | *compute exponents: | |
| 56 | */ | |
| 57 | expo: | |
| 58 | andl3 $EXPMASK,r0,r2 # r2 will hold the exponent of greater operand. | |
| 59 | jeql is_res1 # check for reserved operand. | |
| 60 | shrl $EXPSHIFT,r2,r2 | |
| 61 | ||
| 62 | ||
| 63 | andl3 $EXPMASK,r4,r6 # r6 will hold the exponent of smaller operand. | |
| 64 | jeql is_res2 # check for reserved operand. | |
| 65 | shrl $EXPSHIFT,r6,r6 | |
| 66 | /* | |
| 67 | *compare the exponents: | |
| 68 | */ | |
| 69 | subl3 r6,r2,r8 | |
| 70 | jeql signs | |
| 71 | cmpl r8,$MAX_EXP_DIF | |
| 72 | jlss signs | |
| 73 | ret # return the bigger number. | |
| 74 | ||
| 75 | /* | |
| 76 | *remember the signs: | |
| 77 | */ | |
| 78 | signs: | |
| 79 | clrl r3 | |
| 80 | bbc $31,r0,sign2 # if negative remember it.(R3=1) | |
| 81 | incl r3 | |
| 82 | sign2: | |
| 83 | clrl r7 | |
| 84 | bbc $31,r4,frac # if negative remember it.(R7=1) | |
| 85 | incl r7 | |
| 86 | /* | |
| 87 | *compute 'pure' fraction: | |
| 88 | */ | |
| 89 | frac: | |
| 90 | # clear the non fraction parts. | |
| 91 | andl2 $(0!(EXPMASK | SIGNBIT)),r0 | |
| 92 | # add the hidden bit. | |
| 93 | orl2 $(0!CLEARHID),r0 | |
| 94 | # clear the non fraction parts. | |
| 95 | andl2 $(0!(EXPMASK | SIGNBIT)),r4 | |
| 96 | # add the hidden bit. | |
| 97 | orl2 $(0!CLEARHID),r4 | |
| 98 | ||
| 99 | /* | |
| 100 | *shift the smaller operand: | |
| 101 | */ | |
| 102 | shar r8,r4,r4 | |
| 103 | eql_exps: | |
| 104 | cmpl r3,r7 | |
| 105 | jeql add | |
| 106 | bbc $0,r3,negr4 | |
| 107 | /* | |
| 108 | *negate r0: | |
| 109 | */ | |
| 110 | clrl r3 | |
| 111 | mnegl r0,r0 | |
| 112 | ||
| 113 | /* | |
| 114 | *add the fractions: | |
| 115 | */ | |
| 116 | add: | |
| 117 | clrl r10 | |
| 118 | addl2 r4,r0 | |
| 119 | jgeq norm | |
| 120 | incl r10 | |
| 121 | /* | |
| 122 | *negate the pair r0,r1: | |
| 123 | */ | |
| 124 | mnegl r0,r0 | |
| 125 | norm: callf $4,sfnorm | |
| 126 | ||
| 127 | /* | |
| 128 | *add the sign bit | |
| 129 | */ | |
| 130 | bbs $0,r10,negative | |
| 131 | bbs $0,r3,negative # the bigger operand was negative. | |
| 132 | ret | |
| 133 | negative: | |
| 134 | orl2 $SIGNBIT,r0 | |
| 135 | ret | |
| 136 | ||
| 137 | ||
| 138 | /* | |
| 139 | *negate r4: | |
| 140 | */ | |
| 141 | negr4: | |
| 142 | mnegl r4,r4 | |
| 143 | jmp add | |
| 144 | ||
| 145 | ||
| 146 | is_res1: | |
| 147 | bbs $31,r0,res_op | |
| 148 | movl r4,r0 # return the smaller operand. | |
| 149 | ret | |
| 150 | ||
| 151 | is_res2: | |
| 152 | bbs $31,r4,res_op | |
| 153 | ret # we allready have the 'result' in r0,r1. | |
| 154 | ||
| 155 | res_op: | |
| 156 | callf $4,sfpresop | |
| 157 | ret |