d95af918fa
lots of code copied over, things filled in to hopefully get the LED matrix lighting up. untested.
51 lines
912 B
C
51 lines
912 B
C
/*
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* i8atan2.c
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* begin 20190611 true
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*
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* copied and fixed up from teh internets
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*/
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#include <stdint.h>
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static int8_t iat2(int8_t y, int8_t x)
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{
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return ((y * 32 + (x / 2)) / x) * 2;
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}
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int8_t i8atan2(int8_t y, int8_t x)
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{
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// determine octant
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if (y >= 0) { // oct 0,1,2,3
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if (x >= 0) { // oct 0,1
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if (x > y) {
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return iat2(-y, -x) / 2 + (0 * 32);
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} else {
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if (y == 0) return 0; // (x=0,y=0)
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return -iat2(-x, -y) / 2 + (2 * 32);
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}
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} else { // oct 2,3
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if (x >= -y) {
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return iat2(x, -y) / 2 + (2 * 32);
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} else {
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return -iat2(-y, x) / 2 + (4 * 32);
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}
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}
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} else { // oct 4,5,6,7
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if (x < 0) { // oct 4,5
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if (x < y) {
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return iat2(y, x) / 2 + (-4 * 32);
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} else {
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return -iat2(x, y) / 2 + (-2 * 32);
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}
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} else { // oct 6,7
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if (-x >= y) {
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return iat2(-x, y) / 2 + (-2 * 32);
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} else {
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return -iat2(y, -x) / 2 + (-0 * 32);
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}
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}
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}
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}
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