lib/libm/src/s_sinf.c

   1 /* s_sinf.c -- float version of s_sin.c.
   2  * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
   3  * Optimized by Bruce D. Evans.
   4  */
   5
   6 /*
   7  * ====================================================
   8  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   9  *
  10  * Developed at SunPro, a Sun Microsystems, Inc. business.
  11  * Permission to use, copy, modify, and distribute this
  12  * software is freely granted, provided that this notice
  13  * is preserved.
  14  * ====================================================
  15  *
  16  * $FreeBSD: head/lib/msun/src/s_sinf.c 176569 2008-02-25 22:19:17Z bde $
  17  */
  18
  19 #include <float.h>
  20
  21 #include "math.h"
  22 #define INLINE_KERNEL_COSDF
  23 #define INLINE_KERNEL_SINDF
  24 #define INLINE_REM_PIO2F
  25 #include "math_private.h"
  26 #include "e_rem_pio2f.c"
  27 #include "k_cosf.c"
  28 #include "k_sinf.c"
  29
  30 /* Small multiples of pi/2 rounded to double precision. */
  31 static const double
  32 s1pio2 = 1*M_PI_2,                      /* 0x3FF921FB, 0x54442D18 */
  33 s2pio2 = 2*M_PI_2,                      /* 0x400921FB, 0x54442D18 */
  34 s3pio2 = 3*M_PI_2,                      /* 0x4012D97C, 0x7F3321D2 */
  35 s4pio2 = 4*M_PI_2;                      /* 0x401921FB, 0x54442D18 */
  36
  37 float
  38 sinf(float x)
  39 {
  40         double y;
  41         int32_t n, hx, ix;
  42
  43         GET_FLOAT_WORD(hx,x);
  44         ix = hx & 0x7fffffff;
  45
  46         if(ix <= 0x3f490fda) {          /* |x| ~<= pi/4 */
  47             if(ix<0x39800000)           /* |x| < 2**-12 */
  48                 if(((int)x)==0) return x;       /* x with inexact if x != 0 */
  49             return __kernel_sindf(x);
  50         }
  51         if(ix<=0x407b53d1) {            /* |x| ~<= 5*pi/4 */
  52             if(ix<=0x4016cbe3) {        /* |x| ~<= 3pi/4 */
  53                 if(hx>0)
  54                     return __kernel_cosdf(x - s1pio2);
  55                 else
  56                     return -__kernel_cosdf(x + s1pio2);
  57             } else
  58                 return __kernel_sindf((hx > 0 ? s2pio2 : -s2pio2) - x);
  59         }
  60         if(ix<=0x40e231d5) {            /* |x| ~<= 9*pi/4 */
  61             if(ix<=0x40afeddf) {        /* |x| ~<= 7*pi/4 */
  62                 if(hx>0)
  63                     return -__kernel_cosdf(x - s3pio2);
  64                 else
  65                     return __kernel_cosdf(x + s3pio2);
  66             } else
  67                 return __kernel_sindf(x + (hx > 0 ? -s4pio2 : s4pio2));
  68         }
  69
  70     /* sin(Inf or NaN) is NaN */
  71         else if (ix>=0x7f800000) return x-x;
  72
  73     /* general argument reduction needed */
  74         else {
  75             n = __ieee754_rem_pio2f(x,&y);
  76             switch(n&3) {
  77                 case 0: return  __kernel_sindf(y);
  78                 case 1: return  __kernel_cosdf(y);
  79                 case 2: return  __kernel_sindf(-y);
  80                 default:
  81                         return -__kernel_cosdf(y);
  82             }
  83         }
  84 }