Geralt
c2844a5d32
* Extract rng manipulation to its own file * clang format * Get CPU cycles since game start to use for RNG * change a few things * clang format * Implement suggestions from @ricfehr3 * clang format * Fix rebase issue * clang format * Create RngInfo struct to hold seed and step * clang format * Make a note about rng_restore system not having been tested properly yet * Apply suggestions from @ricfehr3 Co-authored-by: Rickey <ric@rf3.xyz> * clang format --------- Co-authored-by: MathisMartin31 <mathis.martin31@gmail.com> Co-authored-by: Rickey <ric@rf3.xyz>
77 lines
2.1 KiB
C
77 lines
2.1 KiB
C
/**
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* @file random.h
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*
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* @brief Common functions to handle RNG manipulation. Using this interface has three goals:
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* 1. Make RNG repeatable so that people can share seeds and saves, and end up with the same run
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* 2. Prevent the players from engaging in save-scumming since the pseudo-RNG is deterministic
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* 3. Accomodate for base-36 seeds, so that we can freely chose one with alpha-numeric characters in
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* the seed screen input
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*/
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#ifndef RANDOM_H
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#define RANDOM_H
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#include <tonc.h>
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/**
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* @brief Hex value of "ZZZZZZ" in base 36
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*/
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#define MAX_SEED 0x81BF0FFF
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/**
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* @brief Information to track and restore RNG state
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*/
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typedef struct
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{
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/** Initial seed */
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u32 seed;
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/** Position in the rng sequence. */
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u32 step;
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} RngInfo;
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/**
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* @brief Starts counting CPU cycles, this will be used by rng_shuffle_seed to
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* generate a more random seed. To be called once on game start.
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*/
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void rng_init(void);
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/**
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* @brief Update the CPU cycles counter and accumulate it into a bigger u32 `timer_acc` variable.
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*/
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void rng_update(void);
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/**
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* @brief Set the rng seed to the chosen value, and reset the step counter to 0.
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* The seed will be capped at `MAX_SEED` for compatibility with the Seed Input screen
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* used to choose a seed for seeded runs.
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*
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* @param seed the new RNG seed
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*/
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void rng_set_seed(u32 seed);
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/**
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* @brief Uses the CPU cycles counter to randomize the RNG seed as much as possible.
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* This will be called by the main menu and the game over screens so that
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* the next run's seed isn't the same as the last's.
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* rng_start_sampling needs to have been called, and will stop the profiling.
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*/
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void rng_shuffle_seed(void);
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/**
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* @brief Get the next "randomly" generated number in the sequence from the current seed.
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*
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* @return u32
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*/
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u32 rng_get_u32(void);
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/**
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* @brief Restore RNG info struct in the GameVariables. Sets the `seed` and seeks the
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* position `step` in the rng sequence.
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*
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* @param info RngInfo struct applied
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*
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* @note Consistency of the RNG after reloading the RngInfo struct has yet to be tested properly
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*/
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void rng_restore(RngInfo info);
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#endif // RANDOM_H
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