squiggle.c/squiggle.h

#ifndef SQUIGGLEC
#define SQUIGGLEC

// uint32_t header
#include <stdint.h>

// Macros
#define EXIT_ON_ERROR 0
#define MAX_ERROR_LENGTH 500
#define PROCESS_ERROR(...)                                                              \
    do {                                                                                \
        if (EXIT_ON_ERROR) {                                                            \
            printf("@, in %s (%d)", __FILE__, __LINE__);                                \
            exit(1);                                                                    \
        } else {                                                                        \
            char error_msg[MAX_ERROR_LENGTH];                                           \
            snprintf(error_msg, MAX_ERROR_LENGTH, "@, in %s (%d)", __FILE__, __LINE__); \
            struct box error = { .empty = 1, .error_msg = error_msg };                  \
            return error;                                                               \
        }                                                                               \
    } while (0)

// Pseudo Random number generator
uint32_t xorshift32(uint32_t* seed);

// Distribution & sampling functions
float rand_0_to_1(uint32_t* seed);
float rand_float(float max, uint32_t* seed);
float unit_normal(uint32_t* seed);
float random_uniform(float from, float to, uint32_t* seed);
float random_normal(float mean, float sigma, uint32_t* seed);
float random_lognormal(float logmean, float logsigma, uint32_t* seed);
float random_to(float low, float high, uint32_t* seed);

// Array helpers
float array_sum(float* array, int length);
void array_cumsum(float* array_to_sum, float* array_cumsummed, int length);

// Mixture function
float mixture(float (*samplers[])(uint32_t*), float* weights, int n_dists, uint32_t* seed);

// Box
struct box {
    int empty;
    float content;
    char* error_msg;
};

// Inverse cdf
struct box inverse_cdf_float(float cdf(float), float p);
struct box inverse_cdf_box(struct box cdf_box(float), float p);

// Samplers from cdf
struct box sampler_box_cdf(struct box cdf(float), uint32_t* seed);
struct box sampler_float_cdf(float cdf(float), uint32_t* seed);

#endif