1/* Kaddf.s 1.2 86/01/03 */ 2 3#include "fp.h" 4#include "SYS.h" 5 6/* 7 * _Kaddf(acc_most,acc_least,op_most,op_least,hfs) 8 */ 9 .text 10ENTRY(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 */ 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 22next: 23 tstl 12(fp) 24 jneq doit 25 movl $0,r1 26 movl 4(fp),r0 27 ret 28doit: 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 41first_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 # 52expo: 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 # 69signs: 70 clrl r3 71 bbc $31,r0,sign2 # if negative remember it. 72 incl r3 73sign2: 74 clrl r7 75 bbc $31,r4,frac # if negative remember it. 76 incl r7 77 # 78 #compute 'pure' fraction: 79 # 80frac: 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 94eql_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. 107comr0: mcoml r0,r0 108 bbc $0,r9,add 109 incl r0 110 111 # 112 #add the fractions: 113 # 114add: 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. 129comr00: mcoml r0,r0 130 bbc $0,r9,norm 131 incl r0 132norm: pushl 20(fp) # addr of returnen exception. 133 callf $8,_Kfnorm 134 135 # 136 #add the sign bit 137 # 138 bbs $0,r10,negative 139 bbs $0,r3,negative 140 ret 141negative: 142 orl2 $SIGNBIT,r0 143 ret 144 145 146 # 147 #negate the pair r4,r5: 148 # 149negr4r5: 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. 156comr4: 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 165 166