1/* Copyright (c) 2013-2015 Jeffrey Pfau
  2 *
  3 * This Source Code Form is subject to the terms of the Mozilla Public
  4 * License, v. 2.0. If a copy of the MPL was not distributed with this
  5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
  6#ifndef UTIL_MATH_H
  7#define UTIL_MATH_H
  8
  9#include <mgba-util/common.h>
 10
 11CXX_GUARD_START
 12
 13static inline uint32_t popcount32(unsigned bits) {
 14	bits = bits - ((bits >> 1) & 0x55555555);
 15	bits = (bits & 0x33333333) + ((bits >> 2) & 0x33333333);
 16	return (((bits + (bits >> 4)) & 0xF0F0F0F) * 0x1010101) >> 24;
 17}
 18
 19static inline unsigned clz32(uint32_t bits) {
 20#if defined(__GNUC__) || __clang__
 21	if (!bits) {
 22		return 32;
 23	}
 24	return __builtin_clz(bits);
 25#else
 26	static const int table[256] = {
 27		8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
 28		3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
 29		2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
 30		2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
 31		1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 32		1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 33		1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 34		1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
 35		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 36		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 37		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 38		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 39		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 40		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 41		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 42		0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
 43	};
 44
 45	if (bits & 0xFF000000) {
 46		return table[bits >> 24];
 47	} else if (bits & 0x00FF0000) {
 48		return table[bits >> 16] + 8;
 49	} else if (bits & 0x0000FF00) {
 50		return table[bits >> 8] + 16;
 51	}
 52	return table[bits] + 24;
 53#endif
 54}
 55
 56static inline uint32_t toPow2(uint32_t bits) {
 57	if (!bits) {
 58		return 0;
 59	}
 60	unsigned lz = clz32(bits - 1);
 61	return 1 << (32 - lz);
 62}
 63
 64static inline int reduceFraction(int* num, int* den) {
 65	int n = *num;
 66	int d = *den;
 67	while (d != 0) {
 68		int temp = n % d;
 69		n = d;
 70		d = temp;
 71	}
 72	*num /= n;
 73	*den /= n;
 74	return n;
 75}
 76
 77#define TYPE_GENERICIZE(MACRO) \
 78	MACRO(int, Int) \
 79	MACRO(unsigned, UInt)
 80
 81#define LOCK_ASPECT_RATIO(T, t) \
 82	static inline void lockAspectRatio ## t(T refW, T refH, T* w, T* h) { \
 83		if (*w * refH > *h * refW) { \
 84			*w = *h * refW / refH; \
 85		} else if (*w * refH < *h * refW) { \
 86			*h = *w * refH / refW; \
 87		} \
 88	}
 89
 90TYPE_GENERICIZE(LOCK_ASPECT_RATIO)
 91#undef LOCK_ASPECT_RATIO
 92
 93#define LOCK_INTEGER_RATIO(T, t) \
 94	static inline void lockIntegerRatio ## t(T ref, T* val) { \
 95		if (*val >= ref) { \
 96			*val -= *val % ref; \
 97		} \
 98	}
 99
100TYPE_GENERICIZE(LOCK_INTEGER_RATIO)
101#undef LOCK_INTEGER_RATIO
102
103#undef TYPE_GENERICIZE
104CXX_GUARD_END
105
106#endif