// SONIC ROBO BLAST 2 //----------------------------------------------------------------------------- // Copyright (C) 1993-1996 by id Software, Inc. // Copyright (C) 1998-2000 by DooM Legacy Team. // Copyright (C) 2012-2016 by Matthew "Kaito Sinclaire" Walsh. // Copyright (C) 1999-2022 by Sonic Team Junior. // // This program is free software distributed under the // terms of the GNU General Public License, version 2. // See the 'LICENSE' file for more details. //----------------------------------------------------------------------------- /// \file m_random.c /// \brief RNG for client effects and PRNG for game actions #include "doomdef.h" #include "doomtype.h" #include "doomstat.h" // totalplaytime #include "m_random.h" #include "m_fixed.h" // --------------------------- // RNG functions (not synched) // --------------------------- /** Provides a random fixed point number. Distribution is uniform. * As with all M_Random functions, not synched in netgames. * * \return A random fixed point number from [0,1). */ fixed_t M_RandomFixed(void) { #if RAND_MAX < 65535 // Compensate for insufficient randomness. fixed_t rndv = (rand()&1)<<15; return rand()^rndv; #else return (rand() & 0xFFFF); #endif } /** Provides a random byte. Distribution is uniform. * As with all M_Random functions, not synched in netgames. * * \return A random integer from [0, 255]. */ UINT8 M_RandomByte(void) { return (rand() & 0xFF); } /** Provides a random integer for picking random elements from an array. * Distribution is uniform. * As with all M_Random functions, not synched in netgames. * * \param a Number of items in array. * \return A random integer from [0,a). */ INT32 M_RandomKey(INT32 a) { return (INT32)((rand()/((float)RAND_MAX+1.0f))*a); } /** Provides a random integer in a given range. * Distribution is uniform. * As with all M_Random functions, not synched in netgames. * * \param a Lower bound. * \param b Upper bound. * \return A random integer from [a,b]. */ INT32 M_RandomRange(INT32 a, INT32 b) { return (INT32)((rand()/((float)RAND_MAX+1.0f))*(b-a+1))+a; } // ------------------------ // PRNG functions (synched) // ------------------------ // Holds the current seed. static UINT32 randomseed = 0xBADE4404; // Holds the INITIAL seed value. Used for demos, possibly other debugging. static UINT32 initialseed = 0xBADE4404; /** Provides a random fixed point number. * This is a variant of an xorshift PRNG; state fits in a 32 bit integer structure. * * \return A random fixed point number from [0,1). */ ATTRINLINE static fixed_t FUNCINLINE __internal_prng__(void) { randomseed ^= randomseed >> 13; randomseed ^= randomseed >> 11; randomseed ^= randomseed << 21; return ( (randomseed*36548569) >> 4) & (FRACUNIT-1); } /** Provides a random fixed point number. Distribution is uniform. * Literally a wrapper for the internal PRNG function. * * \return A random fixed point number from [0,1). */ #ifndef DEBUGRANDOM fixed_t P_RandomFixed(void) { #else fixed_t P_RandomFixedD(const char *rfile, INT32 rline) { CONS_Printf("P_RandomFixed() at: %sp %d\n", rfile, rline); #endif return __internal_prng__(); } /** Provides a random byte. Distribution is uniform. * If you're curious, (&0xFF00) >> 8 gives the same result * as a fixed point multiplication by 256. * * \return Random integer from [0, 255]. * \sa __internal_prng__ */ #ifndef DEBUGRANDOM UINT8 P_RandomByte(void) { #else UINT8 P_RandomByteD(const char *rfile, INT32 rline) { CONS_Printf("P_RandomByte() at: %sp %d\n", rfile, rline); #endif return (UINT8)((__internal_prng__()&0xFF00)>>8); } /** Provides a random integer for picking random elements from an array. * Distribution is uniform. * NOTE: Maximum range is 65536. * * \param a Number of items in array. * \return A random integer from [0,a). * \sa __internal_prng__ */ #ifndef DEBUGRANDOM INT32 P_RandomKey(INT32 a) { #else INT32 P_RandomKeyD(const char *rfile, INT32 rline, INT32 a) { CONS_Printf("P_RandomKey() at: %sp %d\n", rfile, rline); #endif return (INT32)(((INT64)__internal_prng__() * a) >> FRACBITS); } /** Provides a random integer in a given range. * Distribution is uniform. * NOTE: Maximum range is 65536. * * \param a Lower bound. * \param b Upper bound. * \return A random integer from [a,b]. * \sa __internal_prng__ */ #ifndef DEBUGRANDOM INT32 P_RandomRange(INT32 a, INT32 b) { #else INT32 P_RandomRangeD(const char *rfile, INT32 rline, INT32 a, INT32 b) { CONS_Printf("P_RandomRange() at: %sp %d\n", rfile, rline); #endif return (INT32)(((INT64)__internal_prng__() * (b-a+1)) >> FRACBITS) + a; } // ---------------------- // PRNG seeds & debugging // ---------------------- /** Peeks to see what the next result from the PRNG will be. * Used for debugging. * * \return A 'random' fixed point number from [0,1). * \sa __internal_prng__ */ fixed_t P_RandomPeek(void) { UINT32 r = randomseed; fixed_t ret = __internal_prng__(); randomseed = r; return ret; } /** Gets the current random seed. Used by netgame savegames. * * \return Current random seed. * \sa P_SetRandSeed */ #ifndef DEBUGRANDOM UINT32 P_GetRandSeed(void) { #else UINT32 P_GetRandSeedD(const char *rfile, INT32 rline) { CONS_Printf("P_GetRandSeed() at: %sp %d\n", rfile, rline); #endif return randomseed; } /** Gets the initial random seed. Used by demos. * * \return Initial random seed. * \sa P_SetRandSeed */ #ifndef DEBUGRANDOM UINT32 P_GetInitSeed(void) { #else UINT32 P_GetInitSeedD(const char *rfile, INT32 rline) { CONS_Printf("P_GetInitSeed() at: %sp %d\n", rfile, rline); #endif return initialseed; } /** Sets the random seed. * Used at the beginning of the game, and also for netgames. * * \param rindex New random index. * \sa P_GetRandSeed */ #ifndef DEBUGRANDOM void P_SetRandSeed(UINT32 seed) { #else void P_SetRandSeedD(const char *rfile, INT32 rline, UINT32 seed) { CONS_Printf("P_SetRandSeed() at: %sp %d\n", rfile, rline); #endif // xorshift requires a nonzero seed // this should never happen, but just in case it DOES, we check if (!seed) seed = 0xBADE4404; randomseed = initialseed = seed; } /** Gets a randomized seed for setting the random seed. * * \sa P_GetRandSeed */ UINT32 M_RandomizedSeed(void) { return ((totalplaytime & 0xFFFF) << 16)|M_RandomFixed(); }