gba-trycatch

annotate src/sincos.c @ 3:8e9225853d75

added sincos luts
author John Tsiombikas <nuclear@member.fsf.org>
date Sat, 14 Jun 2014 01:56:58 +0300
parents
children 78d1664c2443
rev   line source
nuclear@3 1 #include <math.h>
nuclear@3 2 #include "sincos.h"
nuclear@3 3 #include "logger.h"
nuclear@3 4
nuclear@3 5 void sincos_init(void)
nuclear@3 6 {
nuclear@3 7 int i;
nuclear@3 8
nuclear@3 9 logmsg(LOG_ALL, "calculating sin/cos lut...\n");
nuclear@3 10
nuclear@3 11 for(i=0; i<SINLUT_SIZE; i++) {
nuclear@3 12 float angle = 2.0 * M_PI * ((float)i / (float)SINLUT_SIZE);
nuclear@3 13 float val = sin(angle);
nuclear@3 14 sinlut[i] = (int16_t)(val * SINLUT_SCALE);
nuclear@3 15 }
nuclear@3 16 }
nuclear@3 17
nuclear@3 18 int16_t sin_int(int16_t norm_angle)
nuclear@3 19 {
nuclear@3 20 norm_angle %= SINLUT_SIZE;
nuclear@3 21 if(norm_angle < 0) {
nuclear@3 22 norm_angle += SINLUT_SIZE;
nuclear@3 23 }
nuclear@3 24 return sinlut[norm_angle];
nuclear@3 25 }
nuclear@3 26
nuclear@3 27 int16_t cos_int(int16_t norm_angle)
nuclear@3 28 {
nuclear@3 29 return sin_int(norm_angle + SINLUT_SIZE / 4);
nuclear@3 30 }
nuclear@3 31
nuclear@3 32 int32_t sin_x16(int32_t radians)
nuclear@3 33 {
nuclear@3 34 int32_t na = (radians << 16) / (M_PI_X16 * 2);
nuclear@3 35 return sin_int((na >> 8) * (SINLUT_SIZE << 8));
nuclear@3 36 }
nuclear@3 37
nuclear@3 38 int32_t cos_x16(int32_t radians)
nuclear@3 39 {
nuclear@3 40 int32_t na = (radians << 16) / (M_PI_X16 * 2);
nuclear@3 41 return cos_int((na >> 8) * (SINLUT_SIZE << 8));
nuclear@3 42 }