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#include <stdint.h>
#include <stdlib.h>
#include <time.h>
#include "fb.h"
#include "rototiller.h"
/* Copyright (C) 2019 - Vito Caputo <vcaputo@pengaru.com> */
/* This implements white noise / snow just using rand() */
typedef union snow_seed_t {
char __padding[256]; /* prevent seeds sharing a cache-line */
int seed;
} snow_seed_t;
typedef struct snow_context_t {
unsigned n_cpus;
snow_seed_t seeds[];
} snow_context_t;
static void * snow_create_context(unsigned ticks, unsigned n_cpus)
{
snow_context_t *ctxt;
ctxt = calloc(1, sizeof(snow_context_t) + n_cpus * sizeof(snow_seed_t));
if (!ctxt)
return NULL;
for (unsigned i = 0; i < n_cpus; i++)
ctxt->seeds[i].seed = rand();
ctxt->n_cpus = n_cpus;
return ctxt;
}
static void snow_destroy_context(void *context)
{
free(context);
}
static int snow_fragmenter(void *context, const fb_fragment_t *fragment, unsigned number, fb_fragment_t *res_fragment)
{
snow_context_t *ctxt = context;
return fb_fragment_slice_single(fragment, ctxt->n_cpus, number, res_fragment);
}
static void snow_prepare_frame(void *context, unsigned ticks, unsigned n_cpus, fb_fragment_t *fragment, rototiller_fragmenter_t *res_fragmenter)
{
*res_fragmenter = snow_fragmenter;
}
static void snow_render_fragment(void *context, unsigned ticks, unsigned cpu, fb_fragment_t *fragment)
{
snow_context_t *ctxt = context;
int *seed = &ctxt->seeds[cpu].seed;
for (unsigned y = fragment->y; y < fragment->y + fragment->height; y++) {
for (unsigned x = fragment->x; x < fragment->x + fragment->width; x++) {
#ifdef __WIN32__
uint32_t pixel = rand();
#else
uint32_t pixel = rand_r(seed) % 256;
#endif
fb_fragment_put_pixel_unchecked(fragment, x, y, pixel << 16 | pixel << 8 | pixel);
}
}
}
rototiller_module_t snow_module = {
.create_context = snow_create_context,
.destroy_context = snow_destroy_context,
.prepare_frame = snow_prepare_frame,
.render_fragment = snow_render_fragment,
.name = "snow",
.description = "TV snow / white noise (threaded)",
.author = "Vito Caputo <vcaputo@pengaru.com>",
.license = "GPLv2",
};
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