[Qemu-devel] [RFC 06/14] vga: 15 and 16bpp draw functions are "swapping" only

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

We now only use vga_draw_line15() and vga_draw_line16() when
byteswapping. Otherwise we have a shared surface. Make this
explicit and remove the reliance on lduw_p which uses
TARGET_WORDS_ENDIAN. We now only rely on the "byteswap" variable
in vga_draw_graphic().

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 hw/display/vga.c          | 22 +++++++++++++---------
 hw/display/vga_template.h | 23 ++++++++++++++++-------
 2 files changed, 29 insertions(+), 16 deletions(-)

diff --git a/hw/display/vga.c b/hw/display/vga.c
index e98f7da..198e192 100644
--- a/hw/display/vga.c
+++ b/hw/display/vga.c
@@ -1342,8 +1342,8 @@ enum {
     VGA_DRAW_LINE4D2,
     VGA_DRAW_LINE8D2,
     VGA_DRAW_LINE8,
-    VGA_DRAW_LINE15,
-    VGA_DRAW_LINE16,
+    VGA_DRAW_LINE15_SWAP,
+    VGA_DRAW_LINE16_SWAP,
     VGA_DRAW_LINE_NB,
 };
 
@@ -1354,8 +1354,8 @@ static vga_draw_line_func * const vga_draw_line_table[VGA_DRAW_LINE_NB] = {
     vga_draw_line4d2,
     vga_draw_line8d2,
     vga_draw_line8,
-    vga_draw_line15,
-    vga_draw_line16,
+    vga_draw_line15_swap,
+    vga_draw_line16_swap,
 };
 
 static int vga_get_bpp(VGACommonState *s)
@@ -1537,12 +1537,15 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
             bits = 8;
             break;
         case 15:
-            v = VGA_DRAW_LINE15;
-            bits = 16;
-            break;
         case 16:
-            v = VGA_DRAW_LINE16;
-            bits = 16;
+            if (byteswap) {
+                v = depth == 15 ? VGA_DRAW_LINE15_SWAP : VGA_DRAW_LINE16_SWAP;
+            } else if (!is_buffer_shared(surface)) {
+                fprintf(stderr,
+                        "vga: Non-shared surface at %dbpp unsupported !\n", depth);
+                return;
+            }
+            bits = depth;
             break;
         case 24:
         case 32:
@@ -1552,6 +1555,7 @@ static void vga_draw_graphic(VGACommonState *s, int full_update)
                 return;
             }
             bits = depth;
+            break;
         }
     }
     if (!is_buffer_shared(surface)) {
diff --git a/hw/display/vga_template.h b/hw/display/vga_template.h
index e7cd9e0..7a44771 100644
--- a/hw/display/vga_template.h
+++ b/hw/display/vga_template.h
@@ -281,18 +281,28 @@ static void vga_draw_line8(VGACommonState *s1, uint8_t *d,
 
 /* XXX: optimize */
 
+/* We have lduw_he_p, lduw_be_p, lduw_le_p but we don't have
+ * lduw_sw_p, as in unconditionally swap :) So let's make it
+ * up here
+ */
+#if defined(HOST_WORDS_BIGENDIAN)
+#define ld_sw_pixel16 lduw_le_p
+#else
+#define ld_sw_pixel16 lduw_be_p
+#endif
+
 /*
  * 15 bit color
  */
-static void vga_draw_line15(VGACommonState *s1, uint8_t *d,
-                            const uint8_t *s, int width)
+static void vga_draw_line15_swap(VGACommonState *s1, uint8_t *d,
+                                 const uint8_t *s, int width)
 {
     int w;
     uint32_t v, r, g, b;
 
     w = width;
     do {
-        v = lduw_p((void *)s);
+        v = ld_sw_pixel16((void *)s);
         r = (v >> 7) & 0xf8;
         g = (v >> 2) & 0xf8;
         b = (v << 3) & 0xf8;
@@ -305,15 +315,15 @@ static void vga_draw_line15(VGACommonState *s1, uint8_t *d,
 /*
  * 16 bit color
  */
-static void vga_draw_line16(VGACommonState *s1, uint8_t *d,
-                            const uint8_t *s, int width)
+static void vga_draw_line16_swap(VGACommonState *s1, uint8_t *d,
+                                 const uint8_t *s, int width)
 {
     int w;
     uint32_t v, r, g, b;
 
     w = width;
     do {
-        v = lduw_p((void *)s);
+        v = ld_sw_pixel16((void *)s);
         r = (v >> 8) & 0xf8;
         g = (v >> 3) & 0xfc;
         b = (v << 3) & 0xf8;
@@ -322,4 +332,3 @@ static void vga_draw_line16(VGACommonState *s1, uint8_t *d,
         d += 4;
     } while (--w != 0);
 }
-
-- 
1.9.1