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Implement random number generator for flecs script
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@SanderMertens
SanderMertens committed Dec 22, 2024
1 parent a33b49c commit 09b90cd
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133 changes: 133 additions & 0 deletions distr/flecs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -56097,6 +56097,101 @@ void flecs_script_register_builtin_functions(
#ifdef FLECS_SCRIPT_MATH
#include <math.h>

typedef struct ecs_script_rng_t {
uint64_t x; /* Current state (initialize with seed) */
uint64_t w; /* Weyl sequence increment */
uint64_t s; /* Constant for Weyl sequence */
int32_t refcount; /* Necessary as flecs script doesn't have ref types */
} ecs_script_rng_t;

static
ecs_script_rng_t* flecs_script_rng_new(void) {
ecs_script_rng_t *result = ecs_os_calloc_t(ecs_script_rng_t);
result->x = 0;
result->w = 0;
result->s = 0xb5ad4eceda1ce2a9; /* Constant for the Weyl sequence */
result->refcount = 1;
return result;
}

static
void flecs_script_rng_keep(ecs_script_rng_t *rng) {
rng->refcount ++;
}

static
void flecs_script_rng_free(ecs_script_rng_t *rng) {
ecs_assert(rng->refcount > 0, ECS_INTERNAL_ERROR, NULL);
if (!--rng->refcount) {
ecs_os_free(rng);
}
}

static
uint64_t flecs_script_rng_next(ecs_script_rng_t *rng) {
rng->x *= rng->x;
rng->x += (rng->w += rng->s);
rng->x = (rng->x >> 32) | (rng->x << 32);
return rng->x;
}

ECS_COMPONENT_DECLARE(EcsScriptRng);

static
ECS_CTOR(EcsScriptRng, ptr, {
ptr->seed = 0;
ptr->impl = flecs_script_rng_new();
})

static
ECS_COPY(EcsScriptRng, dst, src, {
flecs_script_rng_keep(src->impl);
if (dst->impl != src->impl) {
flecs_script_rng_free(dst->impl);
}
dst->seed = src->seed;
dst->impl = src->impl;
})

static
ECS_MOVE(EcsScriptRng, dst, src, {
flecs_script_rng_free(dst->impl);
dst->seed = src->seed;
dst->impl = src->impl;
src->impl = NULL;
})

static
ECS_DTOR(EcsScriptRng, ptr, {
flecs_script_rng_free(ptr->impl);
})

void flecs_script_rng_get_float(
const ecs_function_ctx_t *ctx,
int32_t argc,
const ecs_value_t *argv,
ecs_value_t *result)
{
EcsScriptRng *rng = argv[0].ptr;
uint64_t x = flecs_script_rng_next(rng->impl);
double max = *(double*)argv[1].ptr;
double *r = result->ptr;
*r = (double)x / ((double)UINT64_MAX / max);
}

void flecs_script_rng_get_uint(
const ecs_function_ctx_t *ctx,
int32_t argc,
const ecs_value_t *argv,
ecs_value_t *result)
{
EcsScriptRng *rng = argv[0].ptr;
uint64_t x = flecs_script_rng_next(rng->impl);
uint64_t max = *(uint64_t*)argv[1].ptr;
uint64_t *r = result->ptr;
*r = x % max;
}

#define FLECS_MATH_FUNC_F64(name, ...)\
static\
void flecs_math_##name(\
Expand Down Expand Up @@ -56284,6 +56379,44 @@ void FlecsScriptMathImport(
FLECS_MATH_FUNC_DEF_F64(round, "Round to nearest");

FLECS_MATH_FUNC_DEF_F64(abs, "Compute absolute value");

ecs_set_name_prefix(world, "EcsScript");

ECS_COMPONENT_DEFINE(world, EcsScriptRng);

ecs_set_hooks(world, EcsScriptRng, {
.ctor = ecs_ctor(EcsScriptRng),
.move = ecs_move(EcsScriptRng),
.copy = ecs_copy(EcsScriptRng),
.dtor = ecs_dtor(EcsScriptRng),
});

ecs_struct(world, {
.entity = ecs_id(EcsScriptRng),
.members = {
{ .name = "seed", .type = ecs_id(ecs_u64_t) }
}
});

ecs_method(world, {
.parent = ecs_id(EcsScriptRng),
.name = "f64",
.return_type = ecs_id(ecs_f64_t),
.params = {
{ .name = "max", .type = ecs_id(ecs_f64_t) }
},
.callback = flecs_script_rng_get_float
});

ecs_method(world, {
.parent = ecs_id(EcsScriptRng),
.name = "u64",
.return_type = ecs_id(ecs_u64_t),
.params = {
{ .name = "max", .type = ecs_id(ecs_u64_t) }
},
.callback = flecs_script_rng_get_uint
});
}

#endif
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9 changes: 9 additions & 0 deletions distr/flecs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -14275,6 +14275,15 @@ void FlecsUnitsImport(
extern "C" {
#endif

FLECS_API
extern ECS_COMPONENT_DECLARE(EcsScriptRng);

// Randon number generator
typedef struct {
uint64_t seed;
void *impl;
} EcsScriptRng;

/** Script math import function.
* Usage:
* @code
Expand Down
9 changes: 9 additions & 0 deletions include/flecs/addons/script_math.h
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,15 @@
extern "C" {
#endif

FLECS_API
extern ECS_COMPONENT_DECLARE(EcsScriptRng);

// Randon number generator
typedef struct {
uint64_t seed;
void *impl;
} EcsScriptRng;

/** Script math import function.
* Usage:
* @code
Expand Down
133 changes: 133 additions & 0 deletions src/addons/script/functions_math.c
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,101 @@
#include "script.h"
#include <math.h>

typedef struct ecs_script_rng_t {
uint64_t x; /* Current state (initialize with seed) */
uint64_t w; /* Weyl sequence increment */
uint64_t s; /* Constant for Weyl sequence */
int32_t refcount; /* Necessary as flecs script doesn't have ref types */
} ecs_script_rng_t;

static
ecs_script_rng_t* flecs_script_rng_new(void) {
ecs_script_rng_t *result = ecs_os_calloc_t(ecs_script_rng_t);
result->x = 0;
result->w = 0;
result->s = 0xb5ad4eceda1ce2a9; /* Constant for the Weyl sequence */
result->refcount = 1;
return result;
}

static
void flecs_script_rng_keep(ecs_script_rng_t *rng) {
rng->refcount ++;
}

static
void flecs_script_rng_free(ecs_script_rng_t *rng) {
ecs_assert(rng->refcount > 0, ECS_INTERNAL_ERROR, NULL);
if (!--rng->refcount) {
ecs_os_free(rng);
}
}

static
uint64_t flecs_script_rng_next(ecs_script_rng_t *rng) {
rng->x *= rng->x;
rng->x += (rng->w += rng->s);
rng->x = (rng->x >> 32) | (rng->x << 32);
return rng->x;
}

ECS_COMPONENT_DECLARE(EcsScriptRng);

static
ECS_CTOR(EcsScriptRng, ptr, {
ptr->seed = 0;
ptr->impl = flecs_script_rng_new();
})

static
ECS_COPY(EcsScriptRng, dst, src, {
flecs_script_rng_keep(src->impl);
if (dst->impl != src->impl) {
flecs_script_rng_free(dst->impl);
}
dst->seed = src->seed;
dst->impl = src->impl;
})

static
ECS_MOVE(EcsScriptRng, dst, src, {
flecs_script_rng_free(dst->impl);
dst->seed = src->seed;
dst->impl = src->impl;
src->impl = NULL;
})

static
ECS_DTOR(EcsScriptRng, ptr, {
flecs_script_rng_free(ptr->impl);
})

void flecs_script_rng_get_float(
const ecs_function_ctx_t *ctx,
int32_t argc,
const ecs_value_t *argv,
ecs_value_t *result)
{
EcsScriptRng *rng = argv[0].ptr;
uint64_t x = flecs_script_rng_next(rng->impl);
double max = *(double*)argv[1].ptr;
double *r = result->ptr;
*r = (double)x / ((double)UINT64_MAX / max);
}

void flecs_script_rng_get_uint(
const ecs_function_ctx_t *ctx,
int32_t argc,
const ecs_value_t *argv,
ecs_value_t *result)
{
EcsScriptRng *rng = argv[0].ptr;
uint64_t x = flecs_script_rng_next(rng->impl);
uint64_t max = *(uint64_t*)argv[1].ptr;
uint64_t *r = result->ptr;
*r = x % max;
}

#define FLECS_MATH_FUNC_F64(name, ...)\
static\
void flecs_math_##name(\
Expand Down Expand Up @@ -196,6 +291,44 @@ void FlecsScriptMathImport(
FLECS_MATH_FUNC_DEF_F64(round, "Round to nearest");

FLECS_MATH_FUNC_DEF_F64(abs, "Compute absolute value");

ecs_set_name_prefix(world, "EcsScript");

ECS_COMPONENT_DEFINE(world, EcsScriptRng);

ecs_set_hooks(world, EcsScriptRng, {
.ctor = ecs_ctor(EcsScriptRng),
.move = ecs_move(EcsScriptRng),
.copy = ecs_copy(EcsScriptRng),
.dtor = ecs_dtor(EcsScriptRng),
});

ecs_struct(world, {
.entity = ecs_id(EcsScriptRng),
.members = {
{ .name = "seed", .type = ecs_id(ecs_u64_t) }
}
});

ecs_method(world, {
.parent = ecs_id(EcsScriptRng),
.name = "f64",
.return_type = ecs_id(ecs_f64_t),
.params = {
{ .name = "max", .type = ecs_id(ecs_f64_t) }
},
.callback = flecs_script_rng_get_float
});

ecs_method(world, {
.parent = ecs_id(EcsScriptRng),
.name = "u64",
.return_type = ecs_id(ecs_u64_t),
.params = {
{ .name = "max", .type = ecs_id(ecs_u64_t) }
},
.callback = flecs_script_rng_get_uint
});
}

#endif

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