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#include <stdbool.h> // bool
#include <string.h> // memset()
#include <stdio.h> // fopen()
#include "util.h"
#include "km.h"
#define MAX_BUF_ITEMS (1 << 20)
typedef struct {
FILE *fh;
size_t ofs;
uint64_t buf[MAX_BUF_ITEMS];
} ctx_t;
static inline bool
refill(
ctx_t * const ctx
) {
ctx->ofs = 0;
// D("reading %zu bytes", sizeof(ctx->buf));
return !!fread(ctx->buf, sizeof(ctx->buf), 1, ctx->fh);
}
static bool
next(
ctx_t * const ctx,
uint64_t * const r
) {
if ((ctx->ofs >= MAX_BUF_ITEMS - 1) && !refill(ctx)) {
// return failure
return false;
}
// get next value, increment offset
*r = ctx->buf[ctx->ofs];
ctx->ofs++;
// return success
return true;
}
// get N get_floats
static bool
on_get_floats(
km_rand_t * const rs,
const size_t num_vals,
float * const vals
) {
ctx_t * const ctx = rs->data;
// generate results
for (size_t i = 0; i < num_vals; i++) {
uint64_t v;
if (!next(ctx, &v)) {
// return failure
return false;
}
// add value
vals[i] = 1.0 * v / RAND_MAX;
}
// return success
return true;
}
// fill sizes callback for system random source
static bool
on_get_sizes(
km_rand_t * const rs,
const size_t num_vals,
size_t * const vals
) {
ctx_t * const ctx = rs->data;
// generate results
for (size_t i = 0; i < num_vals; i++) {
uint64_t v;
if (!next(ctx, &v)) {
// return failure
return false;
}
// add value
vals[i] = v;
}
// return success
return true;
}
static void
on_fini(
km_rand_t * const rs
) {
ctx_t * const ctx = rs->data;
// close file
fclose(ctx->fh);
// free context
free(ctx);
rs->data = NULL;
}
// path random source callbacks
static const km_rand_cbs_t
PATH_RAND_CBS = {
.get_floats = on_get_floats,
.get_sizes = on_get_sizes,
.fini = on_fini,
};
// init random source from a file (e.g. "/dev/urandom")
// (NOTE: this method is horribly slow, don't use it)
bool
km_rand_init_path(
km_rand_t * const rs,
const char * const path
) {
// open file
FILE *fh = fopen(path, "rb");
if (!fh) {
// return failure
return false;
}
// alloc context
ctx_t * const ctx = malloc(sizeof(ctx_t));
if (!ctx) {
// return failure
return false;
}
// populate context
ctx->fh = fh;
// fill buffer
if (!refill(ctx)) {
// return failure
return false;
}
// populate random source
rs->cbs = &PATH_RAND_CBS;
rs->data = ctx;
// return success
return true;
}
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