hw/display/bcm2835_fb: Abstract out calculation of pitch, size

Abstract out the calculation of the pitch and size of the
framebuffer into functions that operate on the BCM2835FBConfig
struct -- these are about to get a little more complicated
when we add support for virtual and physical sizes differing.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180814144436.679-6-peter.maydell@linaro.org

hw/display/bcm2835_fb.c

@@ -139,7 +139,7 @@ static void fb_update_display(void *opaque)
         return;
     }
 
-    src_width = s->config.xres * (s->config.bpp >> 3);
+    src_width = bcm2835_fb_get_pitch(&s->config);
     dest_width = s->config.xres;
 
     switch (surface_bits_per_pixel(surface)) {
@@ -204,8 +204,8 @@ static void bcm2835_fb_mbox_push(BCM2835FBState *s, uint32_t value)
 
     /* TODO - Manage properly virtual resolution */
 
-    pitch = s->config.xres * (s->config.bpp >> 3);
-    size = s->config.yres * pitch;
+    pitch = bcm2835_fb_get_pitch(&s->config);
+    size = bcm2835_fb_get_size(&s->config);
 
     stl_le_phys(&s->dma_as, value + 16, pitch);
     stl_le_phys(&s->dma_as, value + 32, s->config.base);

hw/misc/bcm2835_property.c

@@ -146,7 +146,7 @@ static void bcm2835_property_mbox_push(BCM2835PropertyState *s, uint32_t value)
         case 0x00040001: /* Allocate buffer */
             stl_le_phys(&s->dma_as, value + 12, fbconfig.base);
             stl_le_phys(&s->dma_as, value + 16,
-                        fbconfig.xres * fbconfig.yres * fbconfig.bpp / 8);
+                        bcm2835_fb_get_size(&fbconfig));
             resplen = 8;
             break;
         case 0x00048001: /* Release buffer */
@@ -210,7 +210,7 @@ static void bcm2835_property_mbox_push(BCM2835PropertyState *s, uint32_t value)
             break;
         case 0x00040008: /* Get pitch */
             stl_le_phys(&s->dma_as, value + 12,
-                        fbconfig.xres * fbconfig.bpp / 8);
+                        bcm2835_fb_get_pitch(&fbconfig));
             resplen = 4;
             break;
         case 0x00040009: /* Get virtual offset */

include/hw/display/bcm2835_fb.h

@@ -52,4 +52,26 @@ typedef struct {
 
 void bcm2835_fb_reconfigure(BCM2835FBState *s, BCM2835FBConfig *newconfig);
 
+/**
+ * bcm2835_fb_get_pitch: return number of bytes per line of the framebuffer
+ * @config: configuration info for the framebuffer
+ *
+ * Return the number of bytes per line of the framebuffer, ie the number
+ * that must be added to a pixel address to get the address of the pixel
+ * directly below it on screen.
+ */
+static inline uint32_t bcm2835_fb_get_pitch(BCM2835FBConfig *config)
+{
+    return config->xres * (config->bpp >> 3);
+}
+
+/**
+ * bcm2835_fb_get_size: return total size of framebuffer in bytes
+ * @config: configuration info for the framebuffer
+ */
+static inline uint32_t bcm2835_fb_get_size(BCM2835FBConfig *config)
+{
+    return config->yres * bcm2835_fb_get_pitch(config);
+}
+
 #endif