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#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <inttypes.h>
#include <xf86drm.h>
#include <xf86drmMode.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <math.h>
/* Copyright (C) 2016 Vito Caputo <vcaputo@pengaru.com> */
#define exit_if(_cond, _fmt, ...) \
if (_cond) { \
fprintf(stderr, "Fatal error: " _fmt "\n", ##__VA_ARGS__); \
exit(EXIT_FAILURE); \
}
#define pexit_if(_cond, _fmt, ...) \
exit_if(_cond, _fmt ": %s", ##__VA_ARGS__, strerror(errno))
/* Some defines for the fixed-point stuff in render(). */
#define FIXED_TRIG_LUT_SIZE 4096 /* size of the cos/sin look-up tables */
#define FIXED_BITS 12 /* fractional bits */
#define FIXED_EXP 4096 /* 2^FIXED_BITS */
#define FIXED_COS(_rad) costab[_rad % FIXED_TRIG_LUT_SIZE]
#define FIXED_SIN(_rad) sintab[_rad % FIXED_TRIG_LUT_SIZE]
#define FIXED_MULT(_a, _b) ((_a * _b) >> FIXED_BITS)
#define FIXED_NEW(_i) (_i << FIXED_BITS)
#define FIXED_TO_INT(_f) ((_f) >> FIXED_BITS)
/* Draw a rotating checkered 256x256 texture into next_page. */
static void render(uint32_t *current_page, uint32_t *next_page, int width, int height, int pitch) {
static int32_t costab[FIXED_TRIG_LUT_SIZE], sintab[FIXED_TRIG_LUT_SIZE];
static uint8_t texture[256][256];
static int initialized;
static uint32_t colors[2];
static unsigned r, rr;
int y_cos_r, y_sin_r, x_cos_r, x_sin_r, x_cos_r_init, x_sin_r_init, cos_r, sin_r;
int x, y, stride;
uint8_t tx, ty; /* 256x256 texture; 8 bit texture indices to modulo via overflow. */
if (!initialized) {
int i;
initialized = 1;
/* Generate simple checker pattern texture, nothing clever, feel free to play! */
/* If you modify texture on every frame instead of only @ initialization you can
* produce some neat output. These values are indexed into colors[] below. */
for (y = 0; y < 128; y++) {
for (x = 0; x < 128; x++)
texture[y][x] = 1;
for (; x < 256; x++)
texture[y][x] = 0;
}
for (; y < 256; y++) {
for (x = 0; x < 128; x++)
texture[y][x] = 0;
for (; x < 256; x++)
texture[y][x] = 1;
}
/* Generate fixed-point cos & sin LUTs. */
for (i = 0; i < FIXED_TRIG_LUT_SIZE; i++) {
costab[i] = ((cos((double)2*M_PI*i/FIXED_TRIG_LUT_SIZE))*FIXED_EXP);
sintab[i] = ((sin((double)2*M_PI*i/FIXED_TRIG_LUT_SIZE))*FIXED_EXP);
}
}
pitch /= 4; /* pitch is number of bytes in a row, scale it to uint32_t units. */
stride = (pitch - width); /* stride is number of words from row end to start of next row */
/* This is all done using fixed-point in the hopes of being faster, and yes assumptions
* are being made WRT the overflow of tx/ty as well, only tested on x86_64. */
cos_r = FIXED_COS(r);
sin_r = FIXED_SIN(r);
/* Vary the colors, this is just a mashup of sinusoidal rgb values. */
colors[0] = ((FIXED_TO_INT(FIXED_MULT(FIXED_COS(rr), FIXED_NEW(127))) + 128) << 16) |
((FIXED_TO_INT(FIXED_MULT(FIXED_SIN(rr / 2), FIXED_NEW(127))) + 128) << 8) |
((FIXED_TO_INT(FIXED_MULT(FIXED_COS(rr / 3), FIXED_NEW(127))) + 128));
colors[1] = ((FIXED_TO_INT(FIXED_MULT(FIXED_SIN(rr / 2), FIXED_NEW(127))) + 128) << 16) |
((FIXED_TO_INT(FIXED_MULT(FIXED_COS(rr / 2), FIXED_NEW(127))) + 128)) << 8 |
((FIXED_TO_INT(FIXED_MULT(FIXED_SIN(rr), FIXED_NEW(127))) + 128) );
/* The dimensions are cut in half and negated to center the rotation. */
/* The [xy]_{sin,cos}_r variables are accumulators to replace multiplication with addition. */
x_cos_r_init = FIXED_MULT(-FIXED_NEW((width / 2)), cos_r);
x_sin_r_init = FIXED_MULT(-FIXED_NEW((width / 2)), sin_r);
y_cos_r = FIXED_MULT(-FIXED_NEW((height / 2)), cos_r);
y_sin_r = FIXED_MULT(-FIXED_NEW((height / 2)), sin_r);
for (y = 0; y < height; y++) {
x_cos_r = x_cos_r_init;
x_sin_r = x_sin_r_init;
for (x = 0; x < width; x++, next_page++) {
tx = FIXED_TO_INT(x_sin_r - y_cos_r);
ty = FIXED_TO_INT(y_sin_r + x_cos_r);
*next_page = colors[texture[ty][tx]];
x_cos_r += cos_r;
x_sin_r += sin_r;
}
next_page += stride;
y_cos_r += cos_r;
y_sin_r += sin_r;
}
// This governs the rotation and color cycle.
r += FIXED_TO_INT(FIXED_MULT(FIXED_SIN(rr), FIXED_NEW(16)));
rr += 2;
}
int main(int argc, const char *argv[]) {
int drm_fd;
drmModeResPtr drm_res;
drmModeConnectorPtr drm_con;
uint32_t *fb_maps[2], drm_fbs[2];
unsigned page = 0, next_page;
pexit_if(!drmAvailable(),
"drm unavailable");
/* FIXME: use drmOpen(), requires digging to see what you're supposed to supply it for name. */
pexit_if((drm_fd = open("/dev/dri/card0", O_RDWR)) < 0,
"unable to open drm device");
/* this requires root, but doesn't seem necessary for what's being done here, which is a bit surprising. */
// pexit_if(drmSetMaster(drm_fd) < 0,
// "unable to set master");
exit_if(!(drm_res = drmModeGetResources(drm_fd)),
"unable to get drm resources");
exit_if(drm_res->count_connectors < 1 ||
!(drm_con = drmModeGetConnector(drm_fd, drm_res->connectors[0])),
"unable to get first connector");
/* create double-buffers */
struct drm_mode_create_dumb create_dumb = {
.width = drm_con->modes[0].hdisplay,
.height = drm_con->modes[0].vdisplay,
.bpp = 32,
.flags = 0, // unused,
};
pexit_if(ioctl(drm_fd, DRM_IOCTL_MODE_CREATE_DUMB, &create_dumb) < 0,
"unable to create dumb buffer A");
struct drm_mode_map_dumb map_dumb = {
.handle = create_dumb.handle,
.pad = 0, // unused
};
pexit_if(ioctl(drm_fd, DRM_IOCTL_MODE_MAP_DUMB, &map_dumb) < 0,
"unable to prepare dumb buffer A for mmap");
pexit_if(!(fb_maps[0] = mmap(NULL, create_dumb.size, PROT_READ|PROT_WRITE, MAP_SHARED, drm_fd, map_dumb.offset)),
"unable to mmap dumb buffer A");
pexit_if(drmModeAddFB(drm_fd, create_dumb.width, create_dumb.height, 24, create_dumb.bpp, create_dumb.pitch, create_dumb.handle, &drm_fbs[0]) < 0,
"unable to add dumb buffer A as fb");
/* second one... */
pexit_if(ioctl(drm_fd, DRM_IOCTL_MODE_CREATE_DUMB, &create_dumb) < 0,
"unable to create dumb buffer B");
pexit_if(drmModeAddFB(drm_fd, create_dumb.width, create_dumb.height, 24, create_dumb.bpp, create_dumb.pitch, create_dumb.handle, &drm_fbs[1]) < 0,
"unable to add dumb buffer B as fb");
map_dumb.handle = create_dumb.handle;
pexit_if(ioctl(drm_fd, DRM_IOCTL_MODE_MAP_DUMB, &map_dumb) < 0,
"unable to prepare dumb buffer B for mmap");
pexit_if(!(fb_maps[1] = mmap(NULL, create_dumb.size, PROT_READ|PROT_WRITE, MAP_SHARED, drm_fd, map_dumb.offset)),
"unable to mmap dumb buffer B");
/* make the current page the visible one */
pexit_if(drmModeSetCrtc(drm_fd, drm_res->crtcs[0], drm_fbs[page], 0, 0, drm_res->connectors, 1, drm_con->modes) < 0,
"unable to configure crtc");
drmEventContext drm_ev_ctx = {
.version = DRM_EVENT_CONTEXT_VERSION,
.vblank_handler = NULL,
.page_flip_handler = NULL
};
// now the rendering & page-flipping loop */
for (;;page = next_page) {
next_page = (page + 1) % 2;
/* render next page */
render(fb_maps[page], fb_maps[next_page], create_dumb.width, create_dumb.height, create_dumb.pitch);
/* flip synchronously */
pexit_if(drmModePageFlip(drm_fd, drm_res->crtcs[0], drm_fbs[next_page], DRM_MODE_PAGE_FLIP_EVENT, NULL) < 0,
"unable to flip page %u to %u", page, next_page);
drmHandleEvent(drm_fd, &drm_ev_ctx);
}
return EXIT_SUCCESS;
}
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