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1.1 ! root 1: /* ! 2: * Copyright (c) 1987 Regents of the University of California. ! 3: * All rights reserved. ! 4: * ! 5: * Redistribution and use in source and binary forms are permitted ! 6: * provided that: (1) source distributions retain this entire copyright ! 7: * notice and comment, and (2) distributions including binaries display ! 8: * the following acknowledgement: ``This product includes software ! 9: * developed by the University of California, Berkeley and its contributors'' ! 10: * in the documentation or other materials provided with the distribution ! 11: * and in all advertising materials mentioning features or use of this ! 12: * software. Neither the name of the University nor the names of its ! 13: * contributors may be used to endorse or promote products derived ! 14: * from this software without specific prior written permission. ! 15: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR ! 16: * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED ! 17: * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. ! 18: * ! 19: * All recipients should regard themselves as participants in an ongoing ! 20: * research project and hence should feel obligated to report their ! 21: * experiences (good or bad) with these elementary function codes, using ! 22: * the sendbug(8) program, to the authors. ! 23: */ ! 24: .data ! 25: .align 2 ! 26: _sccsid: ! 27: .asciz "@(#)support.s 5.5 (ucb.elefunt) 6/1/90" ! 28: /* ! 29: * copysign(x,y), ! 30: * logb(x), ! 31: * scalb(x,N), ! 32: * finite(x), ! 33: * drem(x,y), ! 34: * Coded in vax assembly language by K. C. Ng 4/9/85. ! 35: * Re-coded in tahoe assembly language by Z. Alex Liu 7/13/87. ! 36: */ ! 37: /* ! 38: * double copysign(x,y) ! 39: * double x,y; ! 40: */ ! 41: .globl _copysign ! 42: .text ! 43: .align 2 ! 44: _copysign: ! 45: .word 0x0004 # save r2 ! 46: movl 8(fp),r1 ! 47: movl 4(fp),r0 # r0:r1 = x ! 48: andl3 $0x7f800000,r0,r2 # r2 = biased exponent of x ! 49: beql 1f # if 0 or reserved op then return x ! 50: andl3 $0x80000000,12(fp),r2 # r2 = sign bit of y at bit-31 ! 51: andl2 $0x7fffffff,r0 # replace x by |x| ! 52: orl2 r2,r0 # copy the sign bit of y to x ! 53: 1: ret ! 54: /* ! 55: * double logb(x) ! 56: * double x; ! 57: */ ! 58: .globl _logb ! 59: .text ! 60: .align 2 ! 61: _logb: ! 62: .word 0x0000 # save nothing ! 63: andl3 $0x7f800000,4(fp),r0 # r0[b23:b30] = biased exponent of x ! 64: beql 1f ! 65: shrl $23,r0,r0 # r0[b0:b7] = biased exponent of x ! 66: subl2 $129,r0 # r0 = unbiased exponent of x ! 67: cvld r0 # acc = unbiased exponent of x (double) ! 68: std r0 # r0 = unbiased exponent of x (double) ! 69: ret ! 70: 1: movl 8(fp),r1 # 8(fp) must be moved first ! 71: movl 4(fp),r0 # r0:r1 = x (zero or reserved op) ! 72: blss 2f # simply return if reserved op ! 73: movl $0xfe000000,r1 ! 74: movl $0xcfffffff,r0 # -2147483647.0 ! 75: 2: ret ! 76: /* ! 77: * long finite(x) ! 78: * double x; ! 79: */ ! 80: .globl _finite ! 81: .text ! 82: .align 2 ! 83: _finite: ! 84: .word 0x0000 # save nothing ! 85: andl3 $0xff800000,4(fp),r0 # r0 = sign of x & its biased exponent ! 86: cmpl r0,$0x80000000 # is x a reserved op? ! 87: beql 1f # if so, return FALSE (0) ! 88: movl $1,r0 # else return TRUE (1) ! 89: ret ! 90: 1: clrl r0 ! 91: ret ! 92: /* ! 93: * double scalb(x,N) ! 94: * double x; int N; ! 95: */ ! 96: .globl _scalb ! 97: .set ERANGE,34 ! 98: .text ! 99: .align 2 ! 100: _scalb: ! 101: .word 0x000c # save r2-r3 ! 102: movl 8(fp),r1 ! 103: movl 4(fp),r0 # r0:r1 = x (-128 <= Ex <= 126) ! 104: andl3 $0x7f800000,r0,r3 # r3[b23:b30] = biased exponent of x ! 105: beql 1f # is x a 0 or a reserved operand? ! 106: movl 12(fp),r2 # r2 = N ! 107: cmpl r2,$0xff # if N >= 255 ! 108: bgeq 2f # then the result must overflow ! 109: cmpl r2,$-0xff # if N <= -255 ! 110: bleq 3f # then the result must underflow ! 111: shrl $23,r3,r3 # r3[b0:b7] = biased exponent of x ! 112: addl2 r2,r3 # r3 = biased exponent of the result ! 113: bleq 3f # if <= 0 then the result underflows ! 114: cmpl r3,$0x100 # if >= 256 then the result overflows ! 115: bgeq 2f ! 116: shll $23,r3,r3 # r3[b23:b30] = biased exponent of res. ! 117: andl2 $0x807fffff,r0 ! 118: orl2 r3,r0 # r0:r1 = x*2^N ! 119: 1: ret ! 120: 2: pushl $ERANGE # if the result would overflow ! 121: callf $8,_infnan # and _infnan returns ! 122: andl3 $0x80000000,4(fp),r2 # get the sign of input arg ! 123: orl2 r2,r0 # re-attach the sign to r0:r1 ! 124: ret ! 125: 3: clrl r1 # if the result would underflow ! 126: clrl r0 # then return 0 ! 127: ret ! 128: /* ! 129: * double drem(x,y) ! 130: * double x,y; ! 131: * Returns x-n*y where n=[x/y] rounded (to even in the half way case). ! 132: */ ! 133: .globl _drem ! 134: .set EDOM,33 ! 135: .text ! 136: .align 2 ! 137: _drem: ! 138: .word 0x1ffc # save r2-r12 ! 139: movl 16(fp),r3 ! 140: movl 12(fp),r2 # r2:r3 = y ! 141: movl 8(fp),r1 ! 142: movl 4(fp),r0 # r0:r1 = x ! 143: andl3 $0xff800000,r0,r4 ! 144: cmpl r4,$0x80000000 # is x a reserved operand? ! 145: beql 1f # if yes then propagate x and return ! 146: andl3 $0xff800000,r2,r4 ! 147: cmpl r4,$0x80000000 # is y a reserved operand? ! 148: bneq 2f ! 149: movl r3,r1 ! 150: movl r2,r0 # if yes then propagate y and return ! 151: 1: ret ! 152: ! 153: 2: tstl r4 # is y a 0? ! 154: bneq 3f ! 155: pushl $EDOM # if so then generate reserved op fault ! 156: callf $8,_infnan ! 157: ret ! 158: ! 159: 3: andl2 $0x7fffffff,r2 # r2:r3 = y <- |y| ! 160: clrl r12 # r12 = nx := 0 ! 161: cmpl r2,$0x1c800000 # Ey ? 57 ! 162: bgtr 4f # if Ey > 57 goto 4 ! 163: addl2 $0x1c800000,r2 # scale up y by 2**57 ! 164: movl $0x1c800000,r12 # r12[b23:b30] = nx = 57 ! 165: 4: pushl r12 # pushed onto stack: nf := nx ! 166: andl3 $0x80000000,r0,-(sp) # pushed onto stack: sign of x ! 167: andl2 $0x7fffffff,r0 # r0:r1 = x <- |x| ! 168: movl r3,r11 # r10:r11 = y1 = y w/ last 27 bits 0 ! 169: andl3 $0xf8000000,r10,r11 # clear last 27 bits of y1 ! 170: ! 171: Loop: cmpd2 r0,r2 # x ? y ! 172: bleq 6f # if x <= y goto 6 ! 173: /* # begin argument reduction */ ! 174: movl r3,r5 ! 175: movl r2,r4 # r4:r5 = t = y ! 176: movl r11,r7 ! 177: movl r10,r6 # r6:r7 = t1 = y1 ! 178: andl3 $0x7f800000,r0,r8 # r8[b23:b30] = Ex:biased exponent of x ! 179: andl3 $0x7f800000,r2,r9 # r9[b23:b30] = Ey:biased exponent of y ! 180: subl2 r9,r8 # r8[b23:b30] = Ex-Ey ! 181: subl2 $0x0c800000,r8 # r8[b23:b30] = k = Ex-Ey-25 ! 182: blss 5f # if k < 0 goto 5 ! 183: addl2 r8,r4 # t += k ! 184: addl2 r8,r6 # t1 += k, scale up t and t1 ! 185: 5: ldd r0 # acc = x ! 186: divd r4 # acc = x/t ! 187: cvdl r8 # r8 = n = [x/t] truncated ! 188: cvld r8 # acc = dble(n) ! 189: std r8 # r8:r9 = dble(n) ! 190: ldd r4 # acc = t ! 191: subd r6 # acc = t-t1 ! 192: muld r8 # acc = n*(t-t1) ! 193: std r4 # r4:r5 = n*(t-t1) ! 194: ldd r6 # acc = t1 ! 195: muld r8 # acc = n*t1 ! 196: subd r0 # acc = n*t1-x ! 197: negd # acc = x-n*t1 ! 198: subd r4 # acc = (x-n*t1)-n*(t-t1) ! 199: std r0 # r0:r1 = (x-n*t1)-n*(t-t1) ! 200: brb Loop ! 201: ! 202: 6: movl r12,r6 # r6 = nx ! 203: beql 7f # if nx == 0 goto 7 ! 204: addl2 r6,r0 # x <- x*2**57:scale x up by nx ! 205: clrl r12 # clear nx ! 206: brb Loop ! 207: ! 208: 7: movl r3,r5 ! 209: movl r2,r4 # r4:r5 = y ! 210: subl2 $0x800000,r4 # r4:r5 = y/2 ! 211: cmpd2 r0,r4 # x ? y/2 ! 212: blss 9f # if x < y/2 goto 9 ! 213: bgtr 8f # if x > y/2 goto 8 ! 214: ldd r8 # acc = dble(n) ! 215: cvdl r8 # r8 = ifix(dble(n)) ! 216: bbc $0,r8,9f # if the last bit is zero, goto 9 ! 217: 8: ldd r0 # acc = x ! 218: subd r2 # acc = x-y ! 219: std r0 # r0:r1 = x-y ! 220: 9: xorl2 (sp)+,r0 # x^sign (exclusive or) ! 221: movl (sp)+,r6 # r6 = nf ! 222: andl3 $0x7f800000,r0,r8 # r8 = biased exponent of x ! 223: andl2 $0x807fffff,r0 # r0 = x w/ exponent zapped ! 224: subl2 r6,r8 # r8 = Ex-nf ! 225: bgtr 0f # if Ex-nf > 0 goto 0 ! 226: clrl r8 # clear r8 ! 227: clrl r0 ! 228: clrl r1 # x underflows to zero ! 229: 0: orl2 r8,r0 # put r8 into x's exponent field ! 230: ret
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