X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=dosdemo;a=blobdiff_plain;f=src%2Fdos%2Fvga.c;h=376e72b22a5c7c0a49438d5445cfc8babc3f259d;hp=c82968488f6164c223e42252f02a8d0279a65a9b;hb=eac1e3782f789d71fe6e232065bf363def77ddf1;hpb=41ed01ac9da8048d41bb030e75e93a4358963f59

diff --git a/src/dos/vga.c b/src/dos/vga.c
index c829684..376e72b 100644
--- a/src/dos/vga.c
+++ b/src/dos/vga.c
@@ -1,5 +1,10 @@
 #include "vga.h"
+#include "vgaregs.h"
 #include "cdpmi.h"
+#include "dosutil.h"
+
+static void crtc_write(int reg, unsigned char val);
+static unsigned char crtc_read(int reg);
 
 int vga_setmode(int mode)
 {
@@ -9,3 +14,57 @@ int vga_setmode(int mode)
 	dpmi_int(0x10, &regs);
 	return 0;
 }
+
+static unsigned short crtc_modex_regs[] = {
+	0x0d06,	/* vertical total */
+	0x3e07,	/* vcount overflow bit */
+	0x4109,	/* double-scan */
+	0xea10,	/* vsync start */
+	0xac11,	/* vsync end & protect */
+	0xdf12,	/* vertical visible */
+	0x0014,	/* no dword mode */
+	0xe715,	/* vblank start */
+	0x0616,	/* vblank end */
+	0xe317,	/* byte mode */
+	0
+};
+
+int vga_setmodex(void)
+{
+	int i;
+	unsigned char val;
+
+	vga_setmode(0x13);
+
+	/* disable chain-4 (C4=0, O/E=1 (sequential), EM=1 (extmem), A/G=0 (gfx) */
+	outpw(VGA_SC_ADDR_PORT, VGA_SC_MEMMODE_REG | 0x0600);
+	/* pull reset low */
+	outpw(VGA_SC_ADDR_PORT, VGA_SC_RESET_REG | 0x0100);
+	/* 25mhz dot clock, 60hz scan */
+	outp(VGA_MISC_PORT, VGA_MISC_480 | VGA_MISC_PG1 | VGA_MISC_CLK25 |
+			VGA_MISC_CPUEN | VGA_MISC_COLOR);
+	/* return reset high */
+	outpw(VGA_SC_ADDR_PORT, VGA_SC_RESET_REG | 0x0300);
+
+	/* disable CRTC write-protect */
+	crtc_write(CRTC_VRETEND_REG, crtc_read(CRTC_VRETEND_REG) & ~CRTC_VRETEND_PR);
+	/* change CRTC registers */
+	for(i=0; crtc_modex_regs[i]; i++) {
+		outpw(VGA_CRTC_PORT, crtc_modex_regs[i]);
+	}
+
+	vga_planemask(0xf);
+	memset(VGA_FBADDR, 3, 320 * 240 / 4);
+	return 0;
+}
+
+static void crtc_write(int reg, unsigned char val)
+{
+	outpw(VGA_CRTC_ADDR_PORT, reg | ((unsigned int)val << 8));
+}
+
+static unsigned char crtc_read(int reg)
+{
+	outp(VGA_CRTC_ADDR_PORT, reg);
+	return inp(VGA_CRTC_DATA_PORT);
+}