Create separate renderer and framebuffer modules

renderer.c

@@ -0,0 +1,112 @@
+#include "renderer.h"
+
+#include "fb.h"
+
+#include <assert.h>
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+#include <xf86drm.h>
+
+static int drm_fd;
+static drmModeConnector *conn;
+static drmModeCrtc *crtc;
+static uint32_t conn_id;
+
+static fb_info_t fbs[2];
+static int front, back;
+
+static uint32_t width, height;
+static void page_flip_handler(int, unsigned, unsigned, unsigned, void *)
+{
+}
+
+static void
+set_pixel(uint32_t x, uint32_t y, uint8_t r, uint8_t g, uint8_t b)
+{
+	/* x %= width; */
+	/* y %= height; */
+	const uint32_t offset = y * (fbs[back].pitch / 4) + x;
+	assert(offset < fbs[back].size);
+	fbs[back].buf[offset] = (r << 16) | (g << 8) | b;
+}
+
+renderer_params_t renderer_init()
+{
+	drm_fd = open("/dev/dri/card1", O_RDWR | O_CLOEXEC);
+	assert(drm_fd != -1);
+
+	drmModeRes *res = drmModeGetResources(drm_fd);
+	assert(res != nullptr);
+	conn = drmModeGetConnector(drm_fd, res->connectors[0]);
+	assert(conn != nullptr);
+	drmModeModeInfo mode = conn->modes[0];
+	conn_id = conn->connector_id;
+
+	fbs[0] = fb_init(drm_fd, mode);
+	fbs[1] = fb_init(drm_fd, mode);
+	front = 0;
+	back = 1;
+
+	const int err = drmModeSetCrtc(
+	    drm_fd, res->crtcs[0], fbs[front].id, 0, 0, &conn_id, 1, &mode);
+	assert(err == 0);
+	crtc = drmModeGetCrtc(drm_fd, res->crtcs[0]);
+	assert(crtc != nullptr);
+
+	drmModeFreeResources(res);
+
+	width = mode.hdisplay;
+	height = mode.vdisplay;
+
+	return (renderer_params_t) {
+		.drm_fd = drm_fd,
+		.aspect = (float)mode.hdisplay / (float)mode.vdisplay,
+	};
+}
+
+void renderer_cleanup()
+{
+	drmModeSetCrtc(
+	    drm_fd, crtc->crtc_id, crtc->buffer_id, crtc->x, crtc->y, &conn_id,
+	    1, &crtc->mode);
+
+	fb_cleanup(drm_fd, fbs[0]);
+	fb_cleanup(drm_fd, fbs[1]);
+	drmModeFreeCrtc(crtc);
+	drmModeFreeConnector(conn);
+	close(drm_fd);
+}
+
+void renderer_handle()
+{
+	drmEventContext ev = {
+		.version = DRM_EVENT_CONTEXT_VERSION,
+		.page_flip_handler = page_flip_handler,
+	};
+	drmHandleEvent(drm_fd, &ev);
+}
+
+void renderer_clear()
+{
+	memset(fbs[back].buf, 0, fbs[back].size);
+}
+
+void renderer_swap()
+{
+	const int err = drmModePageFlip(
+	    drm_fd, crtc->crtc_id, fbs[back].id, DRM_MODE_PAGE_FLIP_EVENT,
+	    nullptr);
+	assert(err == 0);
+
+	front = (front + 1) & 1;
+	back = (back + 1) & 1;
+}
+
+void renderer_draw()
+{
+	for (unsigned y = 0; y < height; ++y) {
+		for (unsigned x = 0; x < width; ++x)
+			set_pixel(x, y, (x * 255) / width, (y * 255) / height, 128);
+	}
+}