cscg22-gearboy

CSCG 2022 Challenge 'Gearboy'
git clone https://git.sinitax.com/sinitax/cscg22-gearboy
Log | Files | Refs | sfeed.txt

rand.h (2233B)

      1/** @file rand.h
      2    Random generator using the linear congruential method
      3
      4    @author	Luc Van den Borre
      5*/
      6#ifndef RAND_INCLUDE
      7#define RAND_INCLUDE
      8
      9#include <types.h>
     10#include <stdint.h>
     11
     12/** Initalise the pseudo-random number generator.
     13
     14    @param seed    The value for initializing the random number generator.
     15
     16    The seed should be different each time, otherwise the same pseudo-random
     17    sequence will be generated.
     18
     19    The DIV Register (@ref DIV_REG) is sometimes used as a seed,
     20    particularly if read at some variable point in time (such
     21    as when the player presses a button).
     22
     23    Only needs to be called once to initialize, but may be called
     24    again to re-initialize with the same or a different seed.
     25
     26    @see rand(), randw()
     27*/
     28#if defined(__PORT_sm83)
     29void initrand(uint16_t seed) OLDCALL;
     30#elif defined(__PORT_z80)
     31void initrand(uint16_t seed) Z88DK_FASTCALL;
     32#endif
     33
     34#define RAND_MAX 255
     35#define RANDW_MAX 65535
     36
     37/** The random number seed is stored in __rand_seed and can be
     38    saved and restored if needed.
     39
     40    \code{.c}
     41    // Save
     42    some_uint16 = __rand_seed;
     43    ...
     44    // Restore
     45    __rand_seed = some_uint16;
     46    \endcode
     47*/
     48extern uint16_t __rand_seed;
     49
     50/** Returns a random byte (8 bit) value.
     51
     52    @ref initrand() should be used to initialize the random number generator before using rand()
     53 */
     54uint8_t rand() OLDCALL;
     55
     56/** Returns a random word (16 bit) value.
     57
     58    @ref initrand() should be used to initialize the random number generator before using rand()
     59 */
     60uint16_t randw() OLDCALL;
     61
     62/** Random generator using the linear lagged additive method
     63
     64    @param seed    The value for initializing the random number generator.
     65
     66    Note: initarand() calls @ref initrand() with the same seed value, and
     67    uses @ref rand() to initialize the random generator.
     68
     69    @see initrand() for suggestions about seed values, arand()
     70*/
     71#if defined(__PORT_sm83)
     72void initarand(uint16_t seed) OLDCALL;
     73#elif defined(__PORT_z80)
     74void initarand(uint16_t seed) Z88DK_FASTCALL;
     75#endif
     76
     77/** Returns a random number generated with the linear lagged additive method.
     78
     79    @ref initarand() should be used to initialize the random number generator before using arand()
     80 */
     81uint8_t arand() OLDCALL;
     82
     83#endif