--- /dev/null
+/* kf_rem_pio2.c -- float version of k_rem_pio2.c
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ */
+
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+#include "fdlibm.h"
+
+/* In the float version, the input parameter x contains 8 bit
+ integers, not 24 bit integers. 113 bit precision is not supported. */
+
+#ifdef __STDC__
+static const int init_jk[] = {4,7,9}; /* initial value for jk */
+#else
+static int init_jk[] = {4,7,9};
+#endif
+
+#ifdef __STDC__
+static const float PIo2[] = {
+#else
+static float PIo2[] = {
+#endif
+ 1.5703125000e+00, /* 0x3fc90000 */
+ 4.5776367188e-04, /* 0x39f00000 */
+ 2.5987625122e-05, /* 0x37da0000 */
+ 7.5437128544e-08, /* 0x33a20000 */
+ 6.0026650317e-11, /* 0x2e840000 */
+ 7.3896444519e-13, /* 0x2b500000 */
+ 5.3845816694e-15, /* 0x27c20000 */
+ 5.6378512969e-18, /* 0x22d00000 */
+ 8.3009228831e-20, /* 0x1fc40000 */
+ 3.2756352257e-22, /* 0x1bc60000 */
+ 6.3331015649e-25, /* 0x17440000 */
+};
+
+#ifdef __STDC__
+static const float
+#else
+static float
+#endif
+zero = 0.0,
+one = 1.0,
+two8 = 2.5600000000e+02, /* 0x43800000 */
+twon8 = 3.9062500000e-03; /* 0x3b800000 */
+
+#ifdef __STDC__
+ int __kernel_rem_pio2f(float *x, float *y, int e0, int nx, int prec, const __int32_t *ipio2)
+#else
+ int __kernel_rem_pio2f(x,y,e0,nx,prec,ipio2)
+ float x[], y[]; int e0,nx,prec; __int32_t ipio2[];
+#endif
+{
+ __int32_t jz,jx,jv,jp,jk,carry,n,iq[20],i,j,k,m,q0,ih;
+ float z,fw,f[20],fq[20],q[20];
+
+ /* initialize jk*/
+ jk = init_jk[prec];
+ jp = jk;
+
+ /* determine jx,jv,q0, note that 3>q0 */
+ jx = nx-1;
+ jv = (e0-3)/8; if(jv<0) jv=0;
+ q0 = e0-8*(jv+1);
+
+ /* set up f[0] to f[jx+jk] where f[jx+jk] = ipio2[jv+jk] */
+ j = jv-jx; m = jx+jk;
+ for(i=0;i<=m;i++,j++) f[i] = (j<0)? zero : (float) ipio2[j];
+
+ /* compute q[0],q[1],...q[jk] */
+ for (i=0;i<=jk;i++) {
+ for(j=0,fw=0.0;j<=jx;j++) fw += x[j]*f[jx+i-j]; q[i] = fw;
+ }
+
+ jz = jk;
+recompute:
+ /* distill q[] into iq[] reversingly */
+ for(i=0,j=jz,z=q[jz];j>0;i++,j--) {
+ fw = (float)((__int32_t)(twon8* z));
+ iq[i] = (__int32_t)(z-two8*fw);
+ z = q[j-1]+fw;
+ }
+
+ /* compute n */
+ z = scalbnf(z,(int)q0); /* actual value of z */
+ z -= (float)8.0*floorf(z*(float)0.125); /* trim off integer >= 8 */
+ n = (__int32_t) z;
+ z -= (float)n;
+ ih = 0;
+ if(q0>0) { /* need iq[jz-1] to determine n */
+ i = (iq[jz-1]>>(8-q0)); n += i;
+ iq[jz-1] -= i<<(8-q0);
+ ih = iq[jz-1]>>(7-q0);
+ }
+ else if(q0==0) ih = iq[jz-1]>>8;
+ else if(z>=(float)0.5) ih=2;
+
+ if(ih>0) { /* q > 0.5 */
+ n += 1; carry = 0;
+ for(i=0;i<jz ;i++) { /* compute 1-q */
+ j = iq[i];
+ if(carry==0) {
+ if(j!=0) {
+ carry = 1; iq[i] = 0x100- j;
+ }
+ } else iq[i] = 0xff - j;
+ }
+ if(q0>0) { /* rare case: chance is 1 in 12 */
+ switch(q0) {
+ case 1:
+ iq[jz-1] &= 0x7f; break;
+ case 2:
+ iq[jz-1] &= 0x3f; break;
+ }
+ }
+ if(ih==2) {
+ z = one - z;
+ if(carry!=0) z -= scalbnf(one,(int)q0);
+ }
+ }
+
+ /* check if recomputation is needed */
+ if(z==zero) {
+ j = 0;
+ for (i=jz-1;i>=jk;i--) j |= iq[i];
+ if(j==0) { /* need recomputation */
+ for(k=1;iq[jk-k]==0;k++); /* k = no. of terms needed */
+
+ for(i=jz+1;i<=jz+k;i++) { /* add q[jz+1] to q[jz+k] */
+ f[jx+i] = (float) ipio2[jv+i];
+ for(j=0,fw=0.0;j<=jx;j++) fw += x[j]*f[jx+i-j];
+ q[i] = fw;
+ }
+ jz += k;
+ goto recompute;
+ }
+ }
+
+ /* chop off zero terms */
+ if(z==(float)0.0) {
+ jz -= 1; q0 -= 8;
+ while(iq[jz]==0) { jz--; q0-=8;}
+ } else { /* break z into 8-bit if necessary */
+ z = scalbnf(z,-(int)q0);
+ if(z>=two8) {
+ fw = (float)((__int32_t)(twon8*z));
+ iq[jz] = (__int32_t)(z-two8*fw);
+ jz += 1; q0 += 8;
+ iq[jz] = (__int32_t) fw;
+ } else iq[jz] = (__int32_t) z ;
+ }
+
+ /* convert integer "bit" chunk to floating-point value */
+ fw = scalbnf(one,(int)q0);
+ for(i=jz;i>=0;i--) {
+ q[i] = fw*(float)iq[i]; fw*=twon8;
+ }
+
+ /* compute PIo2[0,...,jp]*q[jz,...,0] */
+ for(i=jz;i>=0;i--) {
+ for(fw=0.0,k=0;k<=jp&&k<=jz-i;k++) fw += PIo2[k]*q[i+k];
+ fq[jz-i] = fw;
+ }
+
+ /* compress fq[] into y[] */
+ switch(prec) {
+ case 0:
+ fw = 0.0;
+ for (i=jz;i>=0;i--) fw += fq[i];
+ y[0] = (ih==0)? fw: -fw;
+ break;
+ case 1:
+ case 2:
+ fw = 0.0;
+ for (i=jz;i>=0;i--) fw += fq[i];
+ y[0] = (ih==0)? fw: -fw;
+ fw = fq[0]-fw;
+ for (i=1;i<=jz;i++) fw += fq[i];
+ y[1] = (ih==0)? fw: -fw;
+ break;
+ case 3: /* painful */
+ for (i=jz;i>0;i--) {
+ fw = fq[i-1]+fq[i];
+ fq[i] += fq[i-1]-fw;
+ fq[i-1] = fw;
+ }
+ for (i=jz;i>1;i--) {
+ fw = fq[i-1]+fq[i];
+ fq[i] += fq[i-1]-fw;
+ fq[i-1] = fw;
+ }
+ for (fw=0.0,i=jz;i>=2;i--) fw += fq[i];
+ if(ih==0) {
+ y[0] = fq[0]; y[1] = fq[1]; y[2] = fw;
+ } else {
+ y[0] = -fq[0]; y[1] = -fq[1]; y[2] = -fw;
+ }
+ }
+ return n&7;
+}
projects / fw / altos / blobdiff