1/*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * the Systems Programming Group of the University of Utah Computer 7 * Science Department. 8 * 9 * %sccs.include.redist.c% 10 * 11 * @(#)support.s 8.1 (Berkeley) 06/04/93 12 */ 13 14 .text 15 .globl _copysign, _finite, _scalb, _logb, _drem, _pow_P, _atan2__A 16 17| copysign(x,y) 18| returns x with the sign of y. 19_copysign: 20 movl sp@(4),d0 21 movl sp@(8),d1 22 tstw sp@(12) 23 jmi Lneg 24 bclr #31,d0 25 rts 26Lneg: 27 bset #31,d0 28 rts 29 30| finite(x) 31| returns the value TRUE if -INF < x < +INF and returns FALSE otherwise. 32_finite: 33 movw #0x7FF0,d0 34 movw sp@(4),d1 35 andw d0,d1 36 cmpw d0,d1 37 beq Lnotfin 38 moveq #1,d0 39 rts 40Lnotfin: 41 clrl d0 42 rts 43 44| scalb(x, N) 45| returns x * (2**N), for integer values N. 46_scalb: 47 fmoved sp@(4),fp0 48 fbeq Ldone 49 fscalel sp@(12),fp0 50Ldone: 51 fmoved fp0,sp@- 52 movel sp@+,d0 53 movel sp@+,d1 54 rts 55 56| logb(x) 57| returns the unbiased exponent of x, a signed integer in double precision, 58| except that logb(0) is -INF, logb(INF) is +INF, and logb(NAN) is that NAN. 59_logb: 60 movw sp@(4),d0 61 movw #0x7FF0,d1 | exponent bits 62 andw d1,d0 | mask off all else 63 cmpw d1,d0 | max exponent? 64 bne Lfinite | no, is finite 65 fmoved sp@(4),fp0 | yes, infinite or NaN 66 fbun Ldone | NaN returns NaN 67 fabsx fp0 | +-inf returns inf 68 jra Ldone 69Lfinite: 70 fmoved sp@(4),fp0 | get entire number 71 fbne Lnonz | zero? 72 flog2x fp0 | yes, log(0) a convenient source of -inf 73 jra Ldone 74Lnonz: 75 fgetexpx fp0 | get exponent 76 jra Ldone 77 78| drem(x,y) 79| returns x REM y = x - [x/y]*y , where [x/y] is the integer nearest x/y; 80| in half way case, choose the even one. 81_drem: 82 fmoved sp@(4),fp0 83 fremd sp@(12),fp0 84 fmoved fp0,sp@- 85 movel sp@+,d0 86 movel sp@+,d1 87 rts 88 89| pow_P(x,y) 90| return x**y for x with sign=1 and finite y 91_pow_P: 92 flognd sp@(4),fp0 93 fmuld sp@(12),fp0 94 fetoxx fp0 95 fmoved fp0,sp@- 96 movel sp@+,d0 97 movel sp@+,d1 98 rts 99 100| atan2__A(y,x) 101| compute atan2(y,x) where x,y are finite and non-zero 102| called by atan2() after weeding out all the special cases 103_atan2__A: 104 moveq #0,d0 | sign of result 105 fmoved sp@(4),fp0 | get y 106 fboge Lypos | <0? 107 moveq #1,d0 | yes, result is neg 108 fnegx fp0 | make y pos 109Lypos: 110 fmoved sp@(12),fp1 | get x 111 fboge Lxpos | <0? 112 fnegx fp1 | yes, make x pos 113 fdivx fp1,fp0 | y/x 114 fatanx fp0,fp1 | atan(y/x) 115 fmovecr #0,fp0 | get pi 116 fsubx fp1,fp0 | pi - atan(y/x) 117 jra Lsetsign 118Lxpos: 119 fdivx fp1,fp0 | y/x 120 fatanx fp0 | atan(y/x) 121Lsetsign: 122 tstl d0 | should be neg? 123 jeq Lrpos | no, all done 124 fnegx fp0 | yes, negate 125Lrpos: 126 fmoved fp0,sp@- 127 movel sp@+,d0 128 movel sp@+,d1 129 rts 130