display SDL: Split in top and bottom

Split the SDL display driver in a top and bottom
to enable using it with embedded libCs.

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>

drivers/display/CMakeLists.txt

@@ -15,7 +15,6 @@ zephyr_library_sources_ifdef(CONFIG_ILI9488		display_ili9488.c)
 zephyr_library_sources_ifdef(CONFIG_LS0XX		ls0xx.c)
 zephyr_library_sources_ifdef(CONFIG_MAX7219		display_max7219.c)
 zephyr_library_sources_ifdef(CONFIG_OTM8009A		display_otm8009a.c)
-zephyr_library_sources_ifdef(CONFIG_SDL_DISPLAY		display_sdl.c)
 zephyr_library_sources_ifdef(CONFIG_SSD1306		ssd1306.c)
 zephyr_library_sources_ifdef(CONFIG_SSD16XX		ssd16xx.c)
 zephyr_library_sources_ifdef(CONFIG_ST7789V		display_st7789v.c)
@@ -27,3 +26,12 @@ zephyr_library_sources_ifdef(CONFIG_MICROBIT_DISPLAY
 	mb_display.c
 	mb_font.c
 )
+
+if (CONFIG_SDL_DISPLAY)
+	zephyr_library_sources(display_sdl.c)
+	if (CONFIG_NATIVE_APPLICATION)
+		zephyr_library_sources(display_sdl_bottom.c)
+	else()
+		target_sources(native_simulator INTERFACE display_sdl_bottom.c)
+	endif()
+endif()

drivers/display/Kconfig.sdl

@@ -7,7 +7,6 @@ menuconfig SDL_DISPLAY
 	bool "SDL based emulated display"
 	default y
 	depends on DT_HAS_ZEPHYR_SDL_DC_ENABLED
-	depends on EXTERNAL_LIBC
 	select HAS_SDL
 	help
 	  Enable SDL based emulated display compliant with display driver API.

drivers/display/display_sdl.c

@@ -9,10 +9,10 @@
 
 #include <zephyr/drivers/display.h>
 
-#include <SDL.h>
 #include <string.h>
 #include <soc.h>
 #include <zephyr/sys/byteorder.h>
+#include "display_sdl_bottom.h"
 
 #define LOG_LEVEL CONFIG_DISPLAY_LOG_LEVEL
 #include <zephyr/logging/log.h>
@@ -24,9 +24,9 @@ struct sdl_display_config {
 };
 
 struct sdl_display_data {
-	SDL_Window *window;
-	SDL_Renderer *renderer;
-	SDL_Texture *texture;
+	void *window;
+	void *renderer;
+	void *texture;
 	bool display_on;
 	enum display_pixel_format current_pixel_format;
 	uint8_t *buf;
@@ -54,36 +54,15 @@ static int sdl_display_init(const struct device *dev)
 #endif /* SDL_DISPLAY_DEFAULT_PIXEL_FORMAT */
 		;
 
-	disp_data->window =
-	    SDL_CreateWindow("Zephyr Display", SDL_WINDOWPOS_UNDEFINED,
-			     SDL_WINDOWPOS_UNDEFINED, config->width,
-			     config->height, SDL_WINDOW_SHOWN);
-	if (disp_data->window == NULL) {
-		LOG_ERR("Failed to create SDL window: %s", SDL_GetError());
-		return -EIO;
-	}
+	int rc = sdl_display_init_bottom(config->height, config->width, &disp_data->window,
+					 &disp_data->renderer, &disp_data->texture);
 
-	disp_data->renderer =
-	    SDL_CreateRenderer(disp_data->window, -1, SDL_RENDERER_ACCELERATED);
-	if (disp_data->renderer == NULL) {
-		LOG_ERR("Failed to create SDL renderer: %s",
-			    SDL_GetError());
-		return -EIO;
-	}
-
-	disp_data->texture = SDL_CreateTexture(
-	    disp_data->renderer, SDL_PIXELFORMAT_ARGB8888,
-	    SDL_TEXTUREACCESS_STATIC, config->width,
-	    config->height);
-	if (disp_data->texture == NULL) {
-		LOG_ERR("Failed to create SDL texture: %s", SDL_GetError());
+	if (rc != 0) {
+		LOG_ERR("Failed to create SDL display");
 		return -EIO;
 	}
 
 	disp_data->display_on = false;
-	SDL_SetRenderDrawColor(disp_data->renderer, 0, 0, 0, 0xFF);
-	SDL_RenderClear(disp_data->renderer);
-	SDL_RenderPresent(disp_data->renderer);
 
 	return 0;
 }
@@ -222,7 +201,6 @@ static int sdl_display_write(const struct device *dev, const uint16_t x,
 {
 	const struct sdl_display_config *config = dev->config;
 	struct sdl_display_data *disp_data = dev->data;
-	SDL_Rect rect;
 
 	LOG_DBG("Writing %dx%d (w,h) bitmap @ %dx%d (x,y)", desc->width,
 			desc->height, x, y);
@@ -257,20 +235,9 @@ static int sdl_display_write(const struct device *dev, const uint16_t x,
 		sdl_display_write_bgr565(disp_data->buf, desc, buf);
 	}
 
-	rect.x = x;
-	rect.y = y;
-	rect.w = desc->width;
-	rect.h = desc->height;
-
-	SDL_UpdateTexture(disp_data->texture, &rect, disp_data->buf,
-			4 * rect.w);
-
-	if (disp_data->display_on) {
-		SDL_RenderClear(disp_data->renderer);
-		SDL_RenderCopy(disp_data->renderer, disp_data->texture, NULL,
-				NULL);
-		SDL_RenderPresent(disp_data->renderer);
-	}
+	sdl_display_write_bottom(desc->height, desc->width, x, y,
+				 disp_data->renderer, disp_data->texture,
+				 disp_data->buf, disp_data->display_on);
 
 	return 0;
 }
@@ -281,12 +248,6 @@ static int sdl_display_read(const struct device *dev, const uint16_t x,
 			    void *buf)
 {
 	struct sdl_display_data *disp_data = dev->data;
-	SDL_Rect rect;
-
-	rect.x = x;
-	rect.y = y;
-	rect.w = desc->width;
-	rect.h = desc->height;
 
 	LOG_DBG("Reading %dx%d (w,h) bitmap @ %dx%d (x,y)", desc->width,
 			desc->height, x, y);
@@ -295,8 +256,8 @@ static int sdl_display_read(const struct device *dev, const uint16_t x,
 	__ASSERT((desc->pitch * 3U * desc->height) <= desc->buf_size,
 			"Input buffer to small");
 
-	return SDL_RenderReadPixels(disp_data->renderer, &rect, 0, buf,
-			desc->pitch * 4U);
+	return sdl_display_read_bottom(desc->height, desc->width, x, y,
+				       disp_data->renderer, buf, desc->pitch);
 }
 
 static void *sdl_display_get_framebuffer(const struct device *dev)
@@ -312,9 +273,7 @@ static int sdl_display_blanking_off(const struct device *dev)
 
 	disp_data->display_on = true;
 
-	SDL_RenderClear(disp_data->renderer);
-	SDL_RenderCopy(disp_data->renderer, disp_data->texture, NULL, NULL);
-	SDL_RenderPresent(disp_data->renderer);
+	sdl_display_blanking_off_bottom(disp_data->renderer, disp_data->texture);
 
 	return 0;
 }
@@ -327,8 +286,7 @@ static int sdl_display_blanking_on(const struct device *dev)
 
 	disp_data->display_on = false;
 
-	SDL_RenderClear(disp_data->renderer);
-	SDL_RenderPresent(disp_data->renderer);
+	sdl_display_blanking_on_bottom(disp_data->renderer);
 	return 0;
 }
 
@@ -386,20 +344,7 @@ static int sdl_display_set_pixel_format(const struct device *dev,
 
 static void sdl_display_cleanup(struct sdl_display_data *disp_data)
 {
-	if (disp_data->texture != NULL) {
-		SDL_DestroyTexture(disp_data->texture);
-		disp_data->texture = NULL;
-	}
-
-	if (disp_data->renderer != NULL) {
-		SDL_DestroyRenderer(disp_data->renderer);
-		disp_data->renderer = NULL;
-	}
-
-	if (disp_data->window != NULL) {
-		SDL_DestroyWindow(disp_data->window);
-		disp_data->window = NULL;
-	}
+	sdl_display_cleanup_bottom(&disp_data->window, &disp_data->renderer, &disp_data->texture);
 }
 
 static const struct display_driver_api sdl_display_api = {

drivers/display/display_sdl_bottom.c

@@ -0,0 +1,110 @@
+/*
+ * Copyright (c) 2018 Jan Van Winkel <jan.van_winkel@dxplore.eu>
+ * Copyright (c) 2023 Nordic Semiconductor
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <SDL.h>
+#include "nsi_tracing.h"
+
+int sdl_display_init_bottom(uint16_t height, uint16_t width,
+			    void **window, void **renderer, void **texture)
+{
+	*window = SDL_CreateWindow("Zephyr Display", SDL_WINDOWPOS_UNDEFINED,
+				   SDL_WINDOWPOS_UNDEFINED, width,
+				   height, SDL_WINDOW_SHOWN);
+	if (*window == NULL) {
+		nsi_print_warning("Failed to create SDL window: %s", SDL_GetError());
+		return -1;
+	}
+
+	*renderer = SDL_CreateRenderer(*window, -1, SDL_RENDERER_ACCELERATED);
+	if (*renderer == NULL) {
+		nsi_print_warning("Failed to create SDL renderer: %s",
+				SDL_GetError());
+		return -1;
+	}
+
+	*texture = SDL_CreateTexture(*renderer, SDL_PIXELFORMAT_ARGB8888,
+				     SDL_TEXTUREACCESS_STATIC, width, height);
+	if (*texture == NULL) {
+		nsi_print_warning("Failed to create SDL texture: %s", SDL_GetError());
+		return -1;
+	}
+
+	SDL_SetRenderDrawColor(*renderer, 0, 0, 0, 0xFF);
+	SDL_RenderClear(*renderer);
+	SDL_RenderPresent(*renderer);
+
+	return 0;
+}
+
+void sdl_display_write_bottom(const uint16_t height, const uint16_t width,
+			      const uint16_t x, const uint16_t y,
+			      void *renderer, void *texture,
+			      uint8_t *buf, bool display_on)
+{
+	SDL_Rect rect;
+
+	rect.x = x;
+	rect.y = y;
+	rect.w = width;
+	rect.h = height;
+
+	SDL_UpdateTexture(texture, &rect, buf, 4 * rect.w);
+
+	if (display_on) {
+		SDL_RenderClear(renderer);
+		SDL_RenderCopy(renderer, texture, NULL, NULL);
+		SDL_RenderPresent(renderer);
+	}
+}
+
+int sdl_display_read_bottom(const uint16_t height, const uint16_t width,
+			    const uint16_t x, const uint16_t y,
+			    void *renderer, void *buf, uint16_t pitch)
+{
+	SDL_Rect rect;
+
+	rect.x = x;
+	rect.y = y;
+	rect.w = width;
+	rect.h = height;
+
+	return SDL_RenderReadPixels(renderer, &rect, 0, buf, pitch * 4U);
+}
+
+void sdl_display_blanking_off_bottom(void *renderer, void *texture)
+{
+	SDL_RenderClear(renderer);
+	SDL_RenderCopy(renderer, texture, NULL, NULL);
+	SDL_RenderPresent(renderer);
+}
+
+void sdl_display_blanking_on_bottom(void *renderer)
+{
+	SDL_RenderClear(renderer);
+	SDL_RenderPresent(renderer);
+}
+
+void sdl_display_cleanup_bottom(void **window, void **renderer, void **texture)
+{
+	if (*texture != NULL) {
+		SDL_DestroyTexture(*texture);
+		*texture = NULL;
+	}
+
+	if (*renderer != NULL) {
+		SDL_DestroyRenderer(*renderer);
+		*renderer = NULL;
+	}
+
+	if (*window != NULL) {
+		SDL_DestroyWindow(*window);
+		*window = NULL;
+	}
+}

drivers/display/display_sdl_bottom.h

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2018 Jan Van Winkel <jan.van_winkel@dxplore.eu>
+ * Copyright (c) 2023 Nordic Semiconductor
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * "Bottom" of the SDL display driver.
+ * When built with the native_simulator this will be built in the runner context,
+ * that is, with the host C library, and with the host include paths.
+ */
+#ifndef DRIVERS_DISPLAY_DISPLAY_SDL_BOTTOM_H
+#define DRIVERS_DISPLAY_DISPLAY_SDL_BOTTOM_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Note: None of these functions are public interfaces. But internal to the SDL display driver */
+
+int sdl_display_init_bottom(uint16_t height, uint16_t width,
+			    void **window, void **renderer, void **texture);
+void sdl_display_write_bottom(const uint16_t height, const uint16_t width,
+			      const uint16_t x, const uint16_t y,
+			      void *renderer, void *texture,
+			      uint8_t *buf, bool display_on);
+int sdl_display_read_bottom(const uint16_t height, const uint16_t width,
+			    const uint16_t x, const uint16_t y,
+			    void *renderer, void *buf, uint16_t pitch);
+void sdl_display_blanking_off_bottom(void *renderer, void *texture);
+void sdl_display_blanking_on_bottom(void *renderer);
+void sdl_display_cleanup_bottom(void **window, void **renderer, void **texture);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* DRIVERS_DISPLAY_DISPLAY_SDL_BOTTOM_H */