Merge pull request #70 from p96114175/main

Support 16/24/32 bit color depth

Author: jserv

backend/fbdev.c

@@ -40,24 +40,41 @@ typedef struct {
     size_t fb_len;
 } twin_fbdev_t;
 
-static void _twin_fbdev_put_span(twin_coord_t left,
-                                 twin_coord_t top,
-                                 twin_coord_t right,
-                                 twin_argb32_t *pixels,
-                                 void *closure)
-{
-    twin_screen_t *screen = SCREEN(closure);
-    twin_fbdev_t *tx = PRIV(closure);
-
-    if (tx->fb_base == MAP_FAILED)
-        return;
+/* color conversion */
+#define ARGB32_TO_RGB565_PERLINE(dest, pixels, width)   \
+    do {                                                \
+        for (int i = 0; i < width; i++)                 \
+            dest[i] = ((pixels[i] & 0x00f80000) >> 8) | \
+                      ((pixels[i] & 0x0000fc00) >> 5) | \
+                      ((pixels[i] & 0x000000f8) >> 3);  \
+    } while (0)
+
+/* Requires validation in 24-bit per pixel environments */
+#define ARGB32_TO_RGB888_PERLINE(dest, pixels, width) \
+    do {                                              \
+        for (int i = 0; i < width; i++)               \
+            dest[i] = 0xff000000 | pixels[i];         \
+    } while (0)
+
+#define ARGB32_TO_ARGB32_PERLINE(dest, pixels, width) \
+    memcpy(dest, pixels, width * sizeof(*dest))
+
+#define FBDEV_PUT_SPAN_IMPL(bpp, op)                                     \
+    static void _twin_fbdev_put_span##bpp(                               \
+        twin_coord_t left, twin_coord_t top, twin_coord_t right,         \
+        twin_argb32_t *pixels, void *closure)                            \
+    {                                                                    \
+        uint32_t *dest;                                                  \
+        twin_fbdev_t *tx = PRIV(closure);                                \
+        off_t off = sizeof(*dest) * left + top * tx->fb_fix.line_length; \
+        dest = (uint32_t *) ((uintptr_t) tx->fb_base + off);             \
+        twin_coord_t width = right - left;                               \
+        op(dest, pixels, width);                                         \
+    }
 
-    twin_coord_t width = right - left;
-    uint32_t *dest;
-    off_t off = sizeof(*dest) * left + top * tx->fb_fix.line_length;
-    dest = (uint32_t *) ((uintptr_t) tx->fb_base + off);
-    memcpy(dest, pixels, width * sizeof(*dest));
-}
+FBDEV_PUT_SPAN_IMPL(16, ARGB32_TO_RGB565_PERLINE)
+FBDEV_PUT_SPAN_IMPL(24, ARGB32_TO_RGB888_PERLINE)
+FBDEV_PUT_SPAN_IMPL(32, ARGB32_TO_ARGB32_PERLINE)
 
 static void twin_fbdev_get_screen_size(twin_fbdev_t *tx,
                                        int *width,
@@ -85,6 +102,27 @@ static bool twin_fbdev_work(void *closure)
     return true;
 }
 
+static inline bool twin_fbdev_is_rgb565(twin_fbdev_t *tx)
+{
+    return tx->fb_var.red.offset == 11 && tx->fb_var.red.length == 5 &&
+           tx->fb_var.green.offset == 5 && tx->fb_var.green.length == 6 &&
+           tx->fb_var.blue.offset == 0 && tx->fb_var.blue.length == 5;
+}
+
+static inline bool twin_fbdev_is_rgb888(twin_fbdev_t *tx)
+{
+    return tx->fb_var.red.offset == 16 && tx->fb_var.red.length == 8 &&
+           tx->fb_var.green.offset == 8 && tx->fb_var.green.length == 8 &&
+           tx->fb_var.blue.offset == 0 && tx->fb_var.blue.length == 8;
+}
+
+static inline bool twin_fbdev_is_argb32(twin_fbdev_t *tx)
+{
+    return tx->fb_var.red.offset == 16 && tx->fb_var.red.length == 8 &&
+           tx->fb_var.green.offset == 8 && tx->fb_var.green.length == 8 &&
+           tx->fb_var.blue.offset == 0 && tx->fb_var.blue.length == 8;
+}
+
 static bool twin_fbdev_apply_config(twin_fbdev_t *tx)
 {
     /* Read changable information of the framebuffer */
@@ -96,7 +134,6 @@ static bool twin_fbdev_apply_config(twin_fbdev_t *tx)
     /* Set the virtual screen size to be the same as the physical screen */
     tx->fb_var.xres_virtual = tx->fb_var.xres;
     tx->fb_var.yres_virtual = tx->fb_var.yres;
-    tx->fb_var.bits_per_pixel = 32;
     if (ioctl(tx->fb_fd, FBIOPUT_VSCREENINFO, &tx->fb_var) < 0) {
         log_error("Failed to set framebuffer mode");
         return false;
@@ -108,10 +145,29 @@ static bool twin_fbdev_apply_config(twin_fbdev_t *tx)
         return false;
     }
 
-    /* Check bits per pixel */
-    if (tx->fb_var.bits_per_pixel != 32) {
-        log_error("Failed to set framebuffer bpp to 32");
-        return false;
+    /* Examine the framebuffer format */
+    switch (tx->fb_var.bits_per_pixel) {
+    case 16: /* RGB565 */
+        if (!twin_fbdev_is_rgb565(tx)) {
+            log_error("Invalid framebuffer format for 16 bpp");
+            return false;
+        }
+        break;
+    case 24: /* RGB888 */
+        if (!twin_fbdev_is_rgb888(tx)) {
+            log_error("Invalid framebuffer format for 24 bpp");
+            return false;
+        }
+        break;
+    case 32: /* ARGB32 */
+        if (!twin_fbdev_is_argb32(tx)) {
+            log_error("Invalid framebuffer format for 32 bpp");
+            return false;
+        }
+        break;
+    default:
+        log_error("Unsupported bits per pixel: %d", tx->fb_var.bits_per_pixel);
+        break;
     }
 
     /* Read unchangable information of the framebuffer */
@@ -172,9 +228,21 @@ twin_context_t *twin_fbdev_init(int width, int height)
         goto bail_vt_fd;
     }
 
+    /* Examine if framebuffer mapping is valid */
+    if (tx->fb_base == MAP_FAILED) {
+        log_error("Failed to map framebuffer memory");
+        return;
+    }
+
+    const twin_put_span_t fbdev_put_spans[] = {
+        _twin_fbdev_put_span16,
+        _twin_fbdev_put_span24,
+        _twin_fbdev_put_span32,
+    };
     /* Create TWIN screen */
-    ctx->screen =
-        twin_screen_create(width, height, NULL, _twin_fbdev_put_span, ctx);
+    ctx->screen = twin_screen_create(
+        width, height, NULL, fbdev_put_spans[tx->fb_var.bits_per_pixel / 8 - 2],
+        ctx);
 
     /* Create Linux input system object */
     tx->input = twin_linux_input_create(ctx->screen);