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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() */
/* To avoid the contention around rand() I'm just using rand_r()
* in an entirely racy fashion with a single seed from the threaded
* render_fragment(). It should really be per-cpu but the module
* api doesn't currently send down a cpu identifier to the render
* function, so TODO in the future add that.
*/
static int snow_seed;
static int snow_fragmenter(void *context, const fb_fragment_t *fragment, unsigned num, fb_fragment_t *res_fragment)
{
return fb_fragment_slice_single(fragment, 32, num, res_fragment);
}
static void snow_prepare_frame(void *context, unsigned n_cpus, fb_fragment_t *fragment, rototiller_fragmenter_t *res_fragmenter)
{
*res_fragmenter = snow_fragmenter;
}
static void snow_render_fragment(void *context, fb_fragment_t *fragment)
{
for (unsigned y = fragment->y; y < fragment->y + fragment->height; y++) {
for (unsigned x = fragment->x; x < fragment->x + fragment->width; x++) {
uint32_t pixel = rand_r(&snow_seed) % 256;
fb_fragment_put_pixel_unchecked(fragment, x, y, pixel << 16 | pixel << 8 | pixel);
}
}
}
rototiller_module_t snow_module = {
.prepare_frame = snow_prepare_frame,
.render_fragment = snow_render_fragment,
.name = "snow",
.description = "TV snow / white noise",
.author = "Vito Caputo <vcaputo@pengaru.com>",
.license = "GPLv2",
};
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