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114 lines
3.3 KiB
C
114 lines
3.3 KiB
C
#ifndef GUARD_RANDOM_H
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#define GUARD_RANDOM_H
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extern u32 gRngValue;
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extern u32 gRng2Value;
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//Returns a 16-bit pseudorandom number
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u16 Random(void);
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u16 Random2(void);
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//Returns a 32-bit pseudorandom number
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#define Random32() (Random() | (Random() << 16))
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// The number 1103515245 comes from the example implementation of rand and srand
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// in the ISO C standard.
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#define ISO_RANDOMIZE1(val)(1103515245 * (val) + 24691)
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#define ISO_RANDOMIZE2(val)(1103515245 * (val) + 12345)
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//Sets the initial seed value of the pseudorandom number generator
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void SeedRng(u16 seed);
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void SeedRng2(u16 seed);
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/* Structured random number generator.
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* Instead of the caller converting bits from Random() to a meaningful
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* value, the caller provides metadata that is used to return the
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* meaningful value directly. This allows code to interpret the random
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* call, for example, battle tests know what the domain of a random call
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* is, and can exhaustively test it.
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*
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* RandomTag identifies the purpose of the value.
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*
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* RandomUniform(tag, lo, hi) returns a number from lo to hi inclusive
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* with uniform probability.
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*
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* RandomElement(tag, array) returns an element in array with uniform
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* probability. The array must be known at compile-time (e.g. a global
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* const array).
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*
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* RandomPercentage(tag, t) returns FALSE with probability (1-t)/100,
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* and TRUE with probability t/100.
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*
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* RandomWeighted(tag, w0, w1, ... wN) returns a number from 0 to N
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* inclusive. The return value is proportional to the weights, e.g.
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* RandomWeighted(..., 1, 1) returns 50% 0s and 50% 1s.
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* RandomWeighted(..., 2, 1) returns 2/3 0s and 1/3 1s. */
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enum RandomTag
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{
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RNG_NONE,
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RNG_ACCURACY,
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RNG_CONFUSION,
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RNG_CRITICAL_HIT,
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RNG_CUTE_CHARM,
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RNG_DAMAGE_MODIFIER,
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RNG_DIRE_CLAW,
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RNG_FLAME_BODY,
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RNG_FORCE_RANDOM_SWITCH,
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RNG_FROZEN,
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RNG_HOLD_EFFECT_FLINCH,
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RNG_INFATUATION,
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RNG_PARALYSIS,
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RNG_POISON_POINT,
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RNG_RAMPAGE_TURNS,
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RNG_SECONDARY_EFFECT,
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RNG_SLEEP_TURNS,
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RNG_SPEED_TIE,
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RNG_STATIC,
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RNG_STENCH,
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RNG_TRI_ATTACK,
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};
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#define RandomWeighted(tag, ...) \
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({ \
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const u8 weights[] = { __VA_ARGS__ }; \
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u32 sum, i; \
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for (i = 0, sum = 0; i < ARRAY_COUNT(weights); i++) \
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sum += weights[i]; \
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RandomWeightedArray(tag, sum, ARRAY_COUNT(weights), weights); \
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})
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#define RandomPercentage(tag, t) \
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({ \
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u32 r; \
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if (t <= 0) \
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{ \
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r = FALSE; \
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} \
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else if (t >= 100) \
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{ \
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r = TRUE; \
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} \
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else \
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{ \
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const u8 weights[] = { 100 - t, t }; \
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r = RandomWeightedArray(tag, 100, ARRAY_COUNT(weights), weights); \
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} \
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r; \
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})
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#define RandomElement(tag, array) \
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({ \
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*(typeof((array)[0]) *)RandomElementArray(tag, array, sizeof((array)[0]), ARRAY_COUNT(array)); \
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})
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u32 RandomUniform(enum RandomTag, u32 lo, u32 hi);
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u32 RandomWeightedArray(enum RandomTag, u32 sum, u32 n, const u8 *weights);
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const void *RandomElementArray(enum RandomTag, const void *array, size_t size, size_t count);
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u32 RandomUniformDefault(enum RandomTag, u32 lo, u32 hi);
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u32 RandomWeightedArrayDefault(enum RandomTag, u32 sum, u32 n, const u8 *weights);
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const void *RandomElementArrayDefault(enum RandomTag, const void *array, size_t size, size_t count);
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#endif // GUARD_RANDOM_H
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