diff --git a/core/math/expression.cpp b/core/math/expression.cpp index 1040f9e0e43..de7d2d2e2c2 100644 --- a/core/math/expression.cpp +++ b/core/math/expression.cpp @@ -76,7 +76,8 @@ const char *Expression::func_name[Expression::FUNC_MAX] = { "randomize", "randi", "randf", - "rand_range", + "randf_range", + "randi_range", "seed", "rand_seed", "deg2rad", @@ -127,7 +128,7 @@ String Expression::get_func_name(BuiltinFunc p_func) { int Expression::get_func_argument_count(BuiltinFunc p_func) { switch (p_func) { case MATH_RANDOMIZE: - case MATH_RAND: + case MATH_RANDI: case MATH_RANDF: return 0; case MATH_SIN: @@ -178,7 +179,8 @@ int Expression::get_func_argument_count(BuiltinFunc p_func) { case MATH_POW: case MATH_EASE: case MATH_STEPIFY: - case MATH_RANDOM: + case MATH_RANDF_RANGE: + case MATH_RANDI_RANGE: case MATH_POLAR2CARTESIAN: case MATH_CARTESIAN2POLAR: case LOGIC_MAX: @@ -397,17 +399,22 @@ void Expression::exec_func(BuiltinFunc p_func, const Variant **p_inputs, Variant Math::randomize(); } break; - case MATH_RAND: { + case MATH_RANDI: { *r_return = Math::rand(); } break; case MATH_RANDF: { *r_return = Math::randf(); } break; - case MATH_RANDOM: { + case MATH_RANDF_RANGE: { VALIDATE_ARG_NUM(0); VALIDATE_ARG_NUM(1); *r_return = Math::random((double)*p_inputs[0], (double)*p_inputs[1]); } break; + case MATH_RANDI_RANGE: { + VALIDATE_ARG_NUM(0); + VALIDATE_ARG_NUM(1); + *r_return = Math::random((int)*p_inputs[0], (int)*p_inputs[1]); + } break; case MATH_SEED: { VALIDATE_ARG_NUM(0); uint64_t seed = *p_inputs[0]; diff --git a/core/math/expression.h b/core/math/expression.h index f2cfe6b1a6c..80aeb985896 100644 --- a/core/math/expression.h +++ b/core/math/expression.h @@ -73,9 +73,10 @@ public: MATH_MOVE_TOWARD, MATH_DECTIME, MATH_RANDOMIZE, - MATH_RAND, + MATH_RANDI, MATH_RANDF, - MATH_RANDOM, + MATH_RANDF_RANGE, + MATH_RANDI_RANGE, MATH_SEED, MATH_RANDSEED, MATH_DEG2RAD, diff --git a/core/math/math_funcs.cpp b/core/math/math_funcs.cpp index 4154713a873..80413e5c229 100644 --- a/core/math/math_funcs.cpp +++ b/core/math/math_funcs.cpp @@ -181,3 +181,7 @@ double Math::random(double from, double to) { float Math::random(float from, float to) { return default_rand.random(from, to); } + +int Math::random(int from, int to) { + return default_rand.random(from, to); +} diff --git a/core/math/math_funcs.h b/core/math/math_funcs.h index f83ee44f4a7..827637bf2be 100644 --- a/core/math/math_funcs.h +++ b/core/math/math_funcs.h @@ -289,7 +289,7 @@ public: static double random(double from, double to); static float random(float from, float to); - static real_t random(int from, int to) { return (real_t)random((real_t)from, (real_t)to); } + static int random(int from, int to); static _ALWAYS_INLINE_ bool is_equal_approx(real_t a, real_t b) { // Check for exact equality first, required to handle "infinity" values. diff --git a/core/math/random_number_generator.h b/core/math/random_number_generator.h index 2e7941b345b..08e41d6c1ca 100644 --- a/core/math/random_number_generator.h +++ b/core/math/random_number_generator.h @@ -43,7 +43,7 @@ protected: static void _bind_methods(); public: - _FORCE_INLINE_ void set_seed(uint64_t seed) { randbase.seed(seed); } + _FORCE_INLINE_ void set_seed(uint64_t p_seed) { randbase.seed(p_seed); } _FORCE_INLINE_ uint64_t get_seed() { return randbase.get_seed(); } @@ -53,24 +53,11 @@ public: _FORCE_INLINE_ real_t randf() { return randbase.randf(); } - _FORCE_INLINE_ real_t randf_range(real_t from, real_t to) { return randbase.random(from, to); } + _FORCE_INLINE_ real_t randf_range(real_t p_from, real_t p_to) { return randbase.random(p_from, p_to); } - _FORCE_INLINE_ real_t randfn(real_t mean = 0.0, real_t deviation = 1.0) { return randbase.randfn(mean, deviation); } + _FORCE_INLINE_ real_t randfn(real_t p_mean = 0.0, real_t p_deviation = 1.0) { return randbase.randfn(p_mean, p_deviation); } - _FORCE_INLINE_ int randi_range(int from, int to) { - int range; - int min; - if (to > from) { - range = to - from + 1; - min = from; - } else if (to < from) { - range = from - to + 1; - min = to; - } else { // from == to - return from; - } - return randbase.rand(range) + min; - } + _FORCE_INLINE_ int randi_range(int p_from, int p_to) { return randbase.random(p_from, p_to); } RandomNumberGenerator() {} }; diff --git a/core/math/random_pcg.cpp b/core/math/random_pcg.cpp index 02257c38d9e..e0768b9403b 100644 --- a/core/math/random_pcg.cpp +++ b/core/math/random_pcg.cpp @@ -49,3 +49,18 @@ double RandomPCG::random(double p_from, double p_to) { float RandomPCG::random(float p_from, float p_to) { return randf() * (p_to - p_from) + p_from; } + +int RandomPCG::random(int p_from, int p_to) { + int range; + int min; + if (p_to > p_from) { + range = p_to - p_from + 1; + min = p_from; + } else if (p_to < p_from) { + range = p_from - p_to + 1; + min = p_to; + } else { // from == to + return p_from; + } + return rand(range) + min; +} diff --git a/core/math/random_pcg.h b/core/math/random_pcg.h index dfdae53eed8..fe6b1b56397 100644 --- a/core/math/random_pcg.h +++ b/core/math/random_pcg.h @@ -133,7 +133,7 @@ public: double random(double p_from, double p_to); float random(float p_from, float p_to); - real_t random(int p_from, int p_to) { return (real_t)random((real_t)p_from, (real_t)p_to); } + int random(int p_from, int p_to); }; #endif // RANDOM_PCG_H diff --git a/modules/gdscript/doc_classes/@GDScript.xml b/modules/gdscript/doc_classes/@GDScript.xml index e170667a302..95818e5fcfd 100644 --- a/modules/gdscript/doc_classes/@GDScript.xml +++ b/modules/gdscript/doc_classes/@GDScript.xml @@ -921,7 +921,7 @@ [/codeblock] - + @@ -931,7 +931,22 @@ Random range, any floating point value between [code]from[/code] and [code]to[/code]. [codeblock] - prints(rand_range(0, 1), rand_range(0, 1)) # Prints e.g. 0.135591 0.405263 + prints(randf_range(-10, 10), randf_range(-10, 10)) # Prints e.g. -3.844535 7.45315 + [/codeblock] + + + + + + + + + + + Random range, any 32-bit integer value between [code]from[/code] and [code]to[/code] (inclusive). If [code]to[/code] is lesser than [code]from[/code] they are swapped. + [codeblock] + print(randi_range(0, 1)) # Prints 0 or 1 + print(randi_range(-10, 1000)) # Prints any number from -10 to 1000 [/codeblock] diff --git a/modules/gdscript/gdscript_functions.cpp b/modules/gdscript/gdscript_functions.cpp index 31ce63bc6e6..ce4b3ca90c6 100644 --- a/modules/gdscript/gdscript_functions.cpp +++ b/modules/gdscript/gdscript_functions.cpp @@ -83,7 +83,8 @@ const char *GDScriptFunctions::get_func_name(Function p_func) { "randomize", "randi", "randf", - "rand_range", + "randf_range", + "randi_range", "seed", "rand_seed", "deg2rad", @@ -419,7 +420,7 @@ void GDScriptFunctions::call(Function p_func, const Variant **p_args, int p_arg_ Math::randomize(); r_ret = Variant(); } break; - case MATH_RAND: { + case MATH_RANDI: { VALIDATE_ARG_COUNT(0); r_ret = Math::rand(); } break; @@ -427,12 +428,18 @@ void GDScriptFunctions::call(Function p_func, const Variant **p_args, int p_arg_ VALIDATE_ARG_COUNT(0); r_ret = Math::randf(); } break; - case MATH_RANDOM: { + case MATH_RANDF_RANGE: { VALIDATE_ARG_COUNT(2); VALIDATE_ARG_NUM(0); VALIDATE_ARG_NUM(1); r_ret = Math::random((double)*p_args[0], (double)*p_args[1]); } break; + case MATH_RANDI_RANGE: { + VALIDATE_ARG_COUNT(2); + VALIDATE_ARG_NUM(0); + VALIDATE_ARG_NUM(1); + r_ret = Math::random((int)*p_args[0], (int)*p_args[1]); + } break; case MATH_SEED: { VALIDATE_ARG_COUNT(1); VALIDATE_ARG_NUM(0); @@ -1655,7 +1662,7 @@ MethodInfo GDScriptFunctions::get_info(Function p_func) { mi.return_val.type = Variant::NIL; return mi; } break; - case MATH_RAND: { + case MATH_RANDI: { MethodInfo mi("randi"); mi.return_val.type = Variant::INT; return mi; @@ -1665,11 +1672,16 @@ MethodInfo GDScriptFunctions::get_info(Function p_func) { mi.return_val.type = Variant::FLOAT; return mi; } break; - case MATH_RANDOM: { - MethodInfo mi("rand_range", PropertyInfo(Variant::FLOAT, "from"), PropertyInfo(Variant::FLOAT, "to")); + case MATH_RANDF_RANGE: { + MethodInfo mi("randf_range", PropertyInfo(Variant::FLOAT, "from"), PropertyInfo(Variant::FLOAT, "to")); mi.return_val.type = Variant::FLOAT; return mi; } break; + case MATH_RANDI_RANGE: { + MethodInfo mi("randi_range", PropertyInfo(Variant::INT, "from"), PropertyInfo(Variant::INT, "to")); + mi.return_val.type = Variant::INT; + return mi; + } break; case MATH_SEED: { MethodInfo mi("seed", PropertyInfo(Variant::INT, "seed")); mi.return_val.type = Variant::NIL; diff --git a/modules/gdscript/gdscript_functions.h b/modules/gdscript/gdscript_functions.h index 2c6dc029139..ea92808f421 100644 --- a/modules/gdscript/gdscript_functions.h +++ b/modules/gdscript/gdscript_functions.h @@ -73,9 +73,10 @@ public: MATH_MOVE_TOWARD, MATH_DECTIME, MATH_RANDOMIZE, - MATH_RAND, + MATH_RANDI, MATH_RANDF, - MATH_RANDOM, + MATH_RANDF_RANGE, + MATH_RANDI_RANGE, MATH_SEED, MATH_RANDSEED, MATH_DEG2RAD, diff --git a/modules/mono/glue/GodotSharp/GodotSharp/Core/GD.cs b/modules/mono/glue/GodotSharp/GodotSharp/Core/GD.cs index e050d1fdd19..7f4777777c6 100644 --- a/modules/mono/glue/GodotSharp/GodotSharp/Core/GD.cs +++ b/modules/mono/glue/GodotSharp/GodotSharp/Core/GD.cs @@ -129,7 +129,12 @@ namespace Godot public static double RandRange(double from, double to) { - return godot_icall_GD_rand_range(from, to); + return godot_icall_GD_randf_range(from, to); + } + + public static int RandRange(int from, int to) + { + return godot_icall_GD_randi_range(from, to); } public static uint RandSeed(ulong seed, out ulong newSeed) @@ -238,9 +243,11 @@ namespace Godot [MethodImpl(MethodImplOptions.InternalCall)] internal extern static void godot_icall_GD_randomize(); + [MethodImpl(MethodImplOptions.InternalCall)] + internal extern static double godot_icall_GD_randf_range(double from, double to); [MethodImpl(MethodImplOptions.InternalCall)] - internal extern static double godot_icall_GD_rand_range(double from, double to); + internal extern static int godot_icall_GD_randi_range(int from, int to); [MethodImpl(MethodImplOptions.InternalCall)] internal extern static uint godot_icall_GD_rand_seed(ulong seed, out ulong newSeed); diff --git a/modules/mono/glue/gd_glue.cpp b/modules/mono/glue/gd_glue.cpp index 5e892b616b5..133692a88c9 100644 --- a/modules/mono/glue/gd_glue.cpp +++ b/modules/mono/glue/gd_glue.cpp @@ -193,7 +193,11 @@ void godot_icall_GD_randomize() { Math::randomize(); } -double godot_icall_GD_rand_range(double from, double to) { +double godot_icall_GD_randf_range(double from, double to) { + return Math::random(from, to); +} + +int32_t godot_icall_GD_randi_range(int32_t from, int32_t to) { return Math::random(from, to); } @@ -298,7 +302,8 @@ void godot_register_gd_icalls() { mono_add_internal_call("Godot.GD::godot_icall_GD_randf", (void *)godot_icall_GD_randf); mono_add_internal_call("Godot.GD::godot_icall_GD_randi", (void *)godot_icall_GD_randi); mono_add_internal_call("Godot.GD::godot_icall_GD_randomize", (void *)godot_icall_GD_randomize); - mono_add_internal_call("Godot.GD::godot_icall_GD_rand_range", (void *)godot_icall_GD_rand_range); + mono_add_internal_call("Godot.GD::godot_icall_GD_randf_range", (void *)godot_icall_GD_randf_range); + mono_add_internal_call("Godot.GD::godot_icall_GD_randi_range", (void *)godot_icall_GD_randi_range); mono_add_internal_call("Godot.GD::godot_icall_GD_rand_seed", (void *)godot_icall_GD_rand_seed); mono_add_internal_call("Godot.GD::godot_icall_GD_seed", (void *)godot_icall_GD_seed); mono_add_internal_call("Godot.GD::godot_icall_GD_str", (void *)godot_icall_GD_str); diff --git a/modules/visual_script/doc_classes/VisualScriptBuiltinFunc.xml b/modules/visual_script/doc_classes/VisualScriptBuiltinFunc.xml index ef4183e6f60..ca1215b0bd4 100644 --- a/modules/visual_script/doc_classes/VisualScriptBuiltinFunc.xml +++ b/modules/visual_script/doc_classes/VisualScriptBuiltinFunc.xml @@ -111,115 +111,118 @@ Randomize the seed (or the internal state) of the random number generator. Current implementation reseeds using a number based on time. - + Return a random 32 bits integer value. To obtain a random value between 0 to N (where N is smaller than 2^32 - 1), you can use it with the remainder function. Return a random floating-point value between 0 and 1. To obtain a random value between 0 to N, you can use it with multiplication. - + Return a random floating-point value between the two inputs. - + + Return a random 32-bit integer value between the two inputs. + + Set the seed for the random number generator. - + Return a random value from the given seed, along with the new seed. - + Convert the input from degrees to radians. - + Convert the input from radians to degrees. - + Convert the input from linear volume to decibel volume. - + Convert the input from decibel volume to linear volume. - + Converts a 2D point expressed in the polar coordinate system (a distance from the origin [code]r[/code] and an angle [code]th[/code]) to the cartesian coordinate system (X and Y axis). - + Converts a 2D point expressed in the cartesian coordinate system (X and Y axis) to the polar coordinate system (a distance from the origin and an angle). - + - + - + Return the greater of the two numbers, also known as their maximum. - + Return the lesser of the two numbers, also known as their minimum. - + Return the input clamped inside the given range, ensuring the result is never outside it. Equivalent to [code]min(max(input, range_low), range_high)[/code]. - + Return the nearest power of 2 to the input. - + Create a [WeakRef] from the input. - + Create a [FuncRef] from the input. - + Convert between types. - + Return the type of the input as an integer. Check [enum Variant.Type] for the integers that might be returned. - + Checks if a type is registered in the [ClassDB]. - + Return a character with the given ascii value. - + Convert the input to a string. - + Print the given string to the output window. - + Print the given string to the standard error output. - + Print the given string to the standard output, without adding a newline. - + Serialize a [Variant] to a string. - + Deserialize a [Variant] from a string serialized using [constant VAR_TO_STR]. - + Serialize a [Variant] to a [PackedByteArray]. - + Deserialize a [Variant] from a [PackedByteArray] serialized using [constant VAR_TO_BYTES]. - + Return the [Color] with the given name and alpha ranging from 0 to 1. [b]Note:[/b] Names are defined in [code]color_names.inc[/code]. - + Return a number smoothly interpolated between the first two inputs, based on the third input. Similar to [constant MATH_LERP], but interpolates faster at the beginning and slower at the end. Using Hermite interpolation formula: [codeblock] var t = clamp((weight - from) / (to - from), 0.0, 1.0) return t * t * (3.0 - 2.0 * t) [/codeblock] - + - + - + - + Represents the size of the [enum BuiltinFunc] enum. diff --git a/modules/visual_script/visual_script_builtin_funcs.cpp b/modules/visual_script/visual_script_builtin_funcs.cpp index 177f9192b89..6cd4da8b515 100644 --- a/modules/visual_script/visual_script_builtin_funcs.cpp +++ b/modules/visual_script/visual_script_builtin_funcs.cpp @@ -73,7 +73,8 @@ const char *VisualScriptBuiltinFunc::func_name[VisualScriptBuiltinFunc::FUNC_MAX "randomize", "randi", "randf", - "rand_range", + "randf_range", + "randi_range", "seed", "rand_seed", "deg2rad", @@ -143,7 +144,7 @@ bool VisualScriptBuiltinFunc::has_input_sequence_port() const { int VisualScriptBuiltinFunc::get_func_argument_count(BuiltinFunc p_func) { switch (p_func) { case MATH_RANDOMIZE: - case MATH_RAND: + case MATH_RANDI: case MATH_RANDF: return 0; case MATH_SIN: @@ -194,7 +195,8 @@ int VisualScriptBuiltinFunc::get_func_argument_count(BuiltinFunc p_func) { case MATH_POW: case MATH_EASE: case MATH_STEPIFY: - case MATH_RANDOM: + case MATH_RANDF_RANGE: + case MATH_RANDI_RANGE: case MATH_POLAR2CARTESIAN: case MATH_CARTESIAN2POLAR: case LOGIC_MAX: @@ -361,16 +363,23 @@ PropertyInfo VisualScriptBuiltinFunc::get_input_value_port_info(int p_idx) const } } break; case MATH_RANDOMIZE: - case MATH_RAND: + case MATH_RANDI: case MATH_RANDF: { } break; - case MATH_RANDOM: { + case MATH_RANDF_RANGE: { if (p_idx == 0) { return PropertyInfo(Variant::FLOAT, "from"); } else { return PropertyInfo(Variant::FLOAT, "to"); } } break; + case MATH_RANDI_RANGE: { + if (p_idx == 0) { + return PropertyInfo(Variant::INT, "from"); + } else { + return PropertyInfo(Variant::INT, "to"); + } + } break; case MATH_SEED: case MATH_RANDSEED: { return PropertyInfo(Variant::INT, "seed"); @@ -551,13 +560,16 @@ PropertyInfo VisualScriptBuiltinFunc::get_output_value_port_info(int p_idx) cons } break; case MATH_RANDOMIZE: { } break; - case MATH_RAND: { + case MATH_RANDI: { t = Variant::INT; } break; case MATH_RANDF: - case MATH_RANDOM: { + case MATH_RANDF_RANGE: { t = Variant::FLOAT; } break; + case MATH_RANDI_RANGE: { + t = Variant::INT; + } break; case MATH_SEED: { } break; case MATH_RANDSEED: { @@ -861,17 +873,22 @@ void VisualScriptBuiltinFunc::exec_func(BuiltinFunc p_func, const Variant **p_in Math::randomize(); } break; - case VisualScriptBuiltinFunc::MATH_RAND: { + case VisualScriptBuiltinFunc::MATH_RANDI: { *r_return = Math::rand(); } break; case VisualScriptBuiltinFunc::MATH_RANDF: { *r_return = Math::randf(); } break; - case VisualScriptBuiltinFunc::MATH_RANDOM: { + case VisualScriptBuiltinFunc::MATH_RANDF_RANGE: { VALIDATE_ARG_NUM(0); VALIDATE_ARG_NUM(1); *r_return = Math::random((double)*p_inputs[0], (double)*p_inputs[1]); } break; + case VisualScriptBuiltinFunc::MATH_RANDI_RANGE: { + VALIDATE_ARG_NUM(0); + VALIDATE_ARG_NUM(1); + *r_return = Math::random((int)*p_inputs[0], (int)*p_inputs[1]); + } break; case VisualScriptBuiltinFunc::MATH_SEED: { VALIDATE_ARG_NUM(0); uint64_t seed = *p_inputs[0]; @@ -1283,9 +1300,10 @@ void VisualScriptBuiltinFunc::_bind_methods() { BIND_ENUM_CONSTANT(MATH_MOVE_TOWARD); BIND_ENUM_CONSTANT(MATH_DECTIME); BIND_ENUM_CONSTANT(MATH_RANDOMIZE); - BIND_ENUM_CONSTANT(MATH_RAND); + BIND_ENUM_CONSTANT(MATH_RANDI); BIND_ENUM_CONSTANT(MATH_RANDF); - BIND_ENUM_CONSTANT(MATH_RANDOM); + BIND_ENUM_CONSTANT(MATH_RANDF_RANGE); + BIND_ENUM_CONSTANT(MATH_RANDI_RANGE); BIND_ENUM_CONSTANT(MATH_SEED); BIND_ENUM_CONSTANT(MATH_RANDSEED); BIND_ENUM_CONSTANT(MATH_DEG2RAD); @@ -1375,9 +1393,10 @@ void register_visual_script_builtin_func_node() { VisualScriptLanguage::singleton->add_register_func("functions/built_in/move_toward", create_builtin_func_node); VisualScriptLanguage::singleton->add_register_func("functions/built_in/dectime", create_builtin_func_node); VisualScriptLanguage::singleton->add_register_func("functions/built_in/randomize", create_builtin_func_node); - VisualScriptLanguage::singleton->add_register_func("functions/built_in/rand", create_builtin_func_node); + VisualScriptLanguage::singleton->add_register_func("functions/built_in/randi", create_builtin_func_node); VisualScriptLanguage::singleton->add_register_func("functions/built_in/randf", create_builtin_func_node); - VisualScriptLanguage::singleton->add_register_func("functions/built_in/random", create_builtin_func_node); + VisualScriptLanguage::singleton->add_register_func("functions/built_in/randf_range", create_builtin_func_node); + VisualScriptLanguage::singleton->add_register_func("functions/built_in/randi_range", create_builtin_func_node); VisualScriptLanguage::singleton->add_register_func("functions/built_in/seed", create_builtin_func_node); VisualScriptLanguage::singleton->add_register_func("functions/built_in/randseed", create_builtin_func_node); diff --git a/modules/visual_script/visual_script_builtin_funcs.h b/modules/visual_script/visual_script_builtin_funcs.h index aee2ed79cee..b8586730b0d 100644 --- a/modules/visual_script/visual_script_builtin_funcs.h +++ b/modules/visual_script/visual_script_builtin_funcs.h @@ -70,9 +70,10 @@ public: MATH_MOVE_TOWARD, MATH_DECTIME, MATH_RANDOMIZE, - MATH_RAND, + MATH_RANDI, MATH_RANDF, - MATH_RANDOM, + MATH_RANDF_RANGE, + MATH_RANDI_RANGE, MATH_SEED, MATH_RANDSEED, MATH_DEG2RAD, diff --git a/thirdparty/misc/pcg.cpp b/thirdparty/misc/pcg.cpp index 5f4bf404606..914a353874d 100644 --- a/thirdparty/misc/pcg.cpp +++ b/thirdparty/misc/pcg.cpp @@ -25,8 +25,31 @@ void pcg32_srandom_r(pcg32_random_t* rng, uint64_t initstate, uint64_t initseq) } // Source from https://github.com/imneme/pcg-c-basic/blob/master/pcg_basic.c +// pcg32_boundedrand_r(rng, bound): +// Generate a uniformly distributed number, r, where 0 <= r < bound uint32_t pcg32_boundedrand_r(pcg32_random_t *rng, uint32_t bound) { + // To avoid bias, we need to make the range of the RNG a multiple of + // bound, which we do by dropping output less than a threshold. + // A naive scheme to calculate the threshold would be to do + // + // uint32_t threshold = 0x100000000ull % bound; + // + // but 64-bit div/mod is slower than 32-bit div/mod (especially on + // 32-bit platforms). In essence, we do + // + // uint32_t threshold = (0x100000000ull-bound) % bound; + // + // because this version will calculate the same modulus, but the LHS + // value is less than 2^32. uint32_t threshold = -bound % bound; + + // Uniformity guarantees that this loop will terminate. In practice, it + // should usually terminate quickly; on average (assuming all bounds are + // equally likely), 82.25% of the time, we can expect it to require just + // one iteration. In the worst case, someone passes a bound of 2^31 + 1 + // (i.e., 2147483649), which invalidates almost 50% of the range. In + // practice, bounds are typically small and only a tiny amount of the range + // is eliminated. for (;;) { uint32_t r = pcg32_random_r(rng); if (r >= threshold)