From e19a68f5acf441eb0c00cbd38f74e46ad4a288f3 Mon Sep 17 00:00:00 2001
From: Kevin O'Connor <kevin@koconnor.net>
Date: Sat, 14 Jan 2012 14:52:01 -0500
Subject: [PATCH] vgabios: Make cirrus line lengths standard.

Only two modes don't match their expected line length.  One looks like
a bug (it has a virtual line length of 1280 for a screen of 1600
bytes) and one looks like an optimization (2048 vs 1920).  Change the
mode line lengths to exactly match the expected line lengths so that
the VBE code is correct.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
---
 vgasrc/clext.c | 41 +++++++----------------------------------
 vgasrc/vbe.c   |  2 +-
 2 files changed, 8 insertions(+), 35 deletions(-)

diff --git a/vgasrc/clext.c b/vgasrc/clext.c
index 1736843..835d809 100644
--- a/vgasrc/clext.c
+++ b/vgasrc/clext.c
@@ -73,8 +73,8 @@ static u16 ccrtc_640x480x24[] VAR16 = {
     0x2c11,
     0x5f00,0x4f01,0x4f02,0x8003,0x5204,0x1e05,0x0b06,0x3e07,
     0x4009,0x000c,0x000d,
-    0xea10,0xdf12,0x0013,0x4014,0xdf15,0x0b16,0xc317,0xff18,
-    0x001a,0x321b,0x001d,
+    0xea10,0xdf12,0xf013,0x4014,0xdf15,0x0b16,0xc317,0xff18,
+    0x001a,0x221b,0x001d,
     0xffff
 };
 /* 800x600x8 */
@@ -209,7 +209,7 @@ static u16 cseq_1600x1200x8[] VAR16 = {
 static u16 ccrtc_1600x1200x8[] VAR16 = {
     0x2911,0xc300,0x9f01,0x9f02,0x8603,0x8304,0x9405,0x2406,0xf707,
     0x6009,0x000c,0x000d,
-    0x0310,0xff12,0xa013,0x4014,0xff15,0x2416,0xc317,0xff18,
+    0x0310,0xff12,0xc813,0x4014,0xff15,0x2416,0xc317,0xff18,
     0x001a,0x221b,0x001d,
     0xffff
 };
@@ -583,13 +583,14 @@ cirrus_get_bpp_bytes(void)
 static void
 cirrus_set_line_offset(u16 new_line_offset)
 {
+    new_line_offset /= 8;
     u16 crtc_addr = stdvga_get_crtc();
     outb(0x13, crtc_addr);
-    outb(new_line_offset / 8, crtc_addr + 1);
+    outb(new_line_offset, crtc_addr + 1);
 
     outb(0x1b, crtc_addr);
     u8 v = inb(crtc_addr + 1);
-    outb((((new_line_offset / 8) & 0x100) >> 4) | (v & 0xef), crtc_addr + 1);
+    outb(((new_line_offset & 0x100) >> 4) | (v & 0xef), crtc_addr + 1);
 }
 
 static u16
@@ -601,35 +602,7 @@ cirrus_get_line_offset(void)
     outb(0x1b, crtc_addr);
     u8 reg1b = inb(crtc_addr + 1);
 
-    return (((reg1b << 4) & 0x100) + reg13) * 8;
-}
-
-u16
-cirrus_get_line_offset_entry(struct cirrus_mode_s *table_g)
-{
-    u16 *crtc = GET_GLOBAL(table_g->crtc);
-
-    u16 *c = crtc;
-    u16 reg13;
-    for (;;) {
-        reg13 = GET_GLOBAL(*c);
-        if ((reg13 & 0xff) == 0x13)
-            break;
-        c++;
-    }
-    reg13 >>= 8;
-
-    c = crtc;
-    u16 reg1b;
-    for (;;) {
-        reg1b = GET_GLOBAL(*c);
-        if ((reg1b & 0xff) == 0x1b)
-            break;
-        c++;
-    }
-    reg1b >>= 8;
-
-    return (((reg1b << 4) & 0x100) + reg13) * 8;
+    return (((reg1b & 0x10) << 4) + reg13) * 8;
 }
 
 static void
diff --git a/vgasrc/vbe.c b/vgasrc/vbe.c
index ee80e97..14efece 100644
--- a/vgasrc/vbe.c
+++ b/vgasrc/vbe.c
@@ -106,7 +106,7 @@ vbe_104f01(struct bregs *regs)
     SET_FARVAR(seg, info->win_func_ptr.segoff, 0x0);
     int width = GET_GLOBAL(vmode_g->width);
     int height = GET_GLOBAL(vmode_g->height);
-    int linesize = width * DIV_ROUND_UP(depth, 8); // XXX - not always true
+    int linesize = width * DIV_ROUND_UP(depth, 8);
     SET_FARVAR(seg, info->bytes_per_scanline, linesize);
     SET_FARVAR(seg, info->xres, width);
     SET_FARVAR(seg, info->yres, height);
-- 
2.25.1