78 lines
1.8 KiB
C
78 lines
1.8 KiB
C
#include "types.h"
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#ifndef FIXED_H
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#define FIXED_H
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#define FIX_SHIFT 8
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#define HALF_FIX_SHIFT 4
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#define FIX_SCALE ( 1 << FIX_SHIFT )
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#define FIX_SCALE_FLOAT ((float)(FIX_SCALE))
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typedef s32 FIXED;
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static inline FIXED fixed_OverMultiply(FIXED a, FIXED b) {
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// This should multiply two fixed-point numbers sacrificing a little
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// accuracy in exchange for less chance of an overflow
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return ((a >> HALF_FIX_SHIFT) * (b >> HALF_FIX_SHIFT));
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}
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static inline FIXED fixed_multiply (FIXED a, FIXED b) {
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// Multiply two fixed numbers. Possibility of overflow.
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return (a * b) >> FIX_SHIFT;
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}
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static inline FIXED fixed_divide(FIXED a, FIXED b) {
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// Divide two fixed point numbers
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if (b != 0){
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return (a * FIX_SCALE) / b;
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}
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else {
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// Return a large number if division by zero
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// Hopefully this won't break anything :P
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return 100000 << FIX_SHIFT;
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}
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}
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static inline FIXED float_to_fixed(float a) {
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// Convert a float to fixed point
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return ((FIXED)(a * FIX_SCALE_FLOAT));
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}
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static inline float fixed_to_float(FIXED a) {
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// Convert fixed point to float
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return (a / FIX_SCALE_FLOAT);
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}
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static inline void swapFixed(FIXED *a, FIXED *b) {
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// Swap two fixed point integer pointers
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FIXED temp;
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temp = *a;
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*a = *b;
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*b = temp;
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}
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static inline FIXED fixed_sqrt(FIXED a, int iterations) {
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// Calculate square root of a fixed-point number using Binary-Search
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FIXED low = 0;
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FIXED high = a;
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FIXED mid;
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FIXED midSquared;
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for (int i = 0; i < iterations; i++) {
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mid = fixed_divide((low + high), 2 << FIX_SHIFT);
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midSquared = fixed_OverMultiply(mid, mid);
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if (midSquared == a) {
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return mid;
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}
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else if (midSquared > a) {
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high = mid;
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}
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else {
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low = mid;
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}
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}
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return mid;
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}
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#endif // FIXED_H
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