1/* 2 * Copyright (c) 1987, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 .data 8 .align 2 9_sccsid: 10 .asciz "@(#)support.s 8.1 (ucb.elefunt) 06/04/93" 11/* 12 * copysign(x,y), 13 * logb(x), 14 * scalb(x,N), 15 * finite(x), 16 * drem(x,y), 17 * Coded in vax assembly language by K. C. Ng 4/9/85. 18 * Re-coded in tahoe assembly language by Z. Alex Liu 7/13/87. 19 */ 20/* 21 * double copysign(x,y) 22 * double x,y; 23 */ 24 .globl _copysign 25 .text 26 .align 2 27_copysign: 28 .word 0x0004 # save r2 29 movl 8(fp),r1 30 movl 4(fp),r0 # r0:r1 = x 31 andl3 $0x7f800000,r0,r2 # r2 = biased exponent of x 32 beql 1f # if 0 or reserved op then return x 33 andl3 $0x80000000,12(fp),r2 # r2 = sign bit of y at bit-31 34 andl2 $0x7fffffff,r0 # replace x by |x| 35 orl2 r2,r0 # copy the sign bit of y to x 361: ret 37/* 38 * double logb(x) 39 * double x; 40 */ 41 .globl _logb 42 .text 43 .align 2 44_logb: 45 .word 0x0000 # save nothing 46 andl3 $0x7f800000,4(fp),r0 # r0[b23:b30] = biased exponent of x 47 beql 1f 48 shrl $23,r0,r0 # r0[b0:b7] = biased exponent of x 49 subl2 $129,r0 # r0 = unbiased exponent of x 50 cvld r0 # acc = unbiased exponent of x (double) 51 std r0 # r0 = unbiased exponent of x (double) 52 ret 531: movl 8(fp),r1 # 8(fp) must be moved first 54 movl 4(fp),r0 # r0:r1 = x (zero or reserved op) 55 blss 2f # simply return if reserved op 56 movl $0xfe000000,r1 57 movl $0xcfffffff,r0 # -2147483647.0 582: ret 59/* 60 * long finite(x) 61 * double x; 62 */ 63 .globl _finite 64 .text 65 .align 2 66_finite: 67 .word 0x0000 # save nothing 68 andl3 $0xff800000,4(fp),r0 # r0 = sign of x & its biased exponent 69 cmpl r0,$0x80000000 # is x a reserved op? 70 beql 1f # if so, return FALSE (0) 71 movl $1,r0 # else return TRUE (1) 72 ret 731: clrl r0 74 ret 75/* 76 * double scalb(x,N) 77 * double x; int N; 78 */ 79 .globl _scalb 80 .set ERANGE,34 81 .text 82 .align 2 83_scalb: 84 .word 0x000c # save r2-r3 85 movl 8(fp),r1 86 movl 4(fp),r0 # r0:r1 = x (-128 <= Ex <= 126) 87 andl3 $0x7f800000,r0,r3 # r3[b23:b30] = biased exponent of x 88 beql 1f # is x a 0 or a reserved operand? 89 movl 12(fp),r2 # r2 = N 90 cmpl r2,$0xff # if N >= 255 91 bgeq 2f # then the result must overflow 92 cmpl r2,$-0xff # if N <= -255 93 bleq 3f # then the result must underflow 94 shrl $23,r3,r3 # r3[b0:b7] = biased exponent of x 95 addl2 r2,r3 # r3 = biased exponent of the result 96 bleq 3f # if <= 0 then the result underflows 97 cmpl r3,$0x100 # if >= 256 then the result overflows 98 bgeq 2f 99 shll $23,r3,r3 # r3[b23:b30] = biased exponent of res. 100 andl2 $0x807fffff,r0 101 orl2 r3,r0 # r0:r1 = x*2^N 1021: ret 1032: pushl $ERANGE # if the result would overflow 104 callf $8,_infnan # and _infnan returns 105 andl3 $0x80000000,4(fp),r2 # get the sign of input arg 106 orl2 r2,r0 # re-attach the sign to r0:r1 107 ret 1083: clrl r1 # if the result would underflow 109 clrl r0 # then return 0 110 ret 111/* 112 * double drem(x,y) 113 * double x,y; 114 * Returns x-n*y where n=[x/y] rounded (to even in the half way case). 115 */ 116 .globl _drem 117 .set EDOM,33 118 .text 119 .align 2 120_drem: 121 .word 0x1ffc # save r2-r12 122 movl 16(fp),r3 123 movl 12(fp),r2 # r2:r3 = y 124 movl 8(fp),r1 125 movl 4(fp),r0 # r0:r1 = x 126 andl3 $0xff800000,r0,r4 127 cmpl r4,$0x80000000 # is x a reserved operand? 128 beql 1f # if yes then propagate x and return 129 andl3 $0xff800000,r2,r4 130 cmpl r4,$0x80000000 # is y a reserved operand? 131 bneq 2f 132 movl r3,r1 133 movl r2,r0 # if yes then propagate y and return 1341: ret 135 1362: tstl r4 # is y a 0? 137 bneq 3f 138 pushl $EDOM # if so then generate reserved op fault 139 callf $8,_infnan 140 ret 141 1423: andl2 $0x7fffffff,r2 # r2:r3 = y <- |y| 143 clrl r12 # r12 = nx := 0 144 cmpl r2,$0x1c800000 # Ey ? 57 145 bgtr 4f # if Ey > 57 goto 4 146 addl2 $0x1c800000,r2 # scale up y by 2**57 147 movl $0x1c800000,r12 # r12[b23:b30] = nx = 57 1484: pushl r12 # pushed onto stack: nf := nx 149 andl3 $0x80000000,r0,-(sp) # pushed onto stack: sign of x 150 andl2 $0x7fffffff,r0 # r0:r1 = x <- |x| 151 movl r3,r11 # r10:r11 = y1 = y w/ last 27 bits 0 152 andl3 $0xf8000000,r10,r11 # clear last 27 bits of y1 153 154Loop: cmpd2 r0,r2 # x ? y 155 bleq 6f # if x <= y goto 6 156 /* # begin argument reduction */ 157 movl r3,r5 158 movl r2,r4 # r4:r5 = t = y 159 movl r11,r7 160 movl r10,r6 # r6:r7 = t1 = y1 161 andl3 $0x7f800000,r0,r8 # r8[b23:b30] = Ex:biased exponent of x 162 andl3 $0x7f800000,r2,r9 # r9[b23:b30] = Ey:biased exponent of y 163 subl2 r9,r8 # r8[b23:b30] = Ex-Ey 164 subl2 $0x0c800000,r8 # r8[b23:b30] = k = Ex-Ey-25 165 blss 5f # if k < 0 goto 5 166 addl2 r8,r4 # t += k 167 addl2 r8,r6 # t1 += k, scale up t and t1 1685: ldd r0 # acc = x 169 divd r4 # acc = x/t 170 cvdl r8 # r8 = n = [x/t] truncated 171 cvld r8 # acc = dble(n) 172 std r8 # r8:r9 = dble(n) 173 ldd r4 # acc = t 174 subd r6 # acc = t-t1 175 muld r8 # acc = n*(t-t1) 176 std r4 # r4:r5 = n*(t-t1) 177 ldd r6 # acc = t1 178 muld r8 # acc = n*t1 179 subd r0 # acc = n*t1-x 180 negd # acc = x-n*t1 181 subd r4 # acc = (x-n*t1)-n*(t-t1) 182 std r0 # r0:r1 = (x-n*t1)-n*(t-t1) 183 brb Loop 184 1856: movl r12,r6 # r6 = nx 186 beql 7f # if nx == 0 goto 7 187 addl2 r6,r0 # x <- x*2**57:scale x up by nx 188 clrl r12 # clear nx 189 brb Loop 190 1917: movl r3,r5 192 movl r2,r4 # r4:r5 = y 193 subl2 $0x800000,r4 # r4:r5 = y/2 194 cmpd2 r0,r4 # x ? y/2 195 blss 9f # if x < y/2 goto 9 196 bgtr 8f # if x > y/2 goto 8 197 ldd r8 # acc = dble(n) 198 cvdl r8 # r8 = ifix(dble(n)) 199 bbc $0,r8,9f # if the last bit is zero, goto 9 2008: ldd r0 # acc = x 201 subd r2 # acc = x-y 202 std r0 # r0:r1 = x-y 2039: xorl2 (sp)+,r0 # x^sign (exclusive or) 204 movl (sp)+,r6 # r6 = nf 205 andl3 $0x7f800000,r0,r8 # r8 = biased exponent of x 206 andl2 $0x807fffff,r0 # r0 = x w/ exponent zapped 207 subl2 r6,r8 # r8 = Ex-nf 208 bgtr 0f # if Ex-nf > 0 goto 0 209 clrl r8 # clear r8 210 clrl r0 211 clrl r1 # x underflows to zero 2120: orl2 r8,r0 # put r8 into x's exponent field 213 ret 214