Added support for multiple fonts

andreas-jonsson · Nov 4, 2023 · 0386856 · 0386856
1 parent 3510267
commit 0386856
Show file tree

Hide file tree

Showing 7 changed files with 26 additions and 275 deletions.
diff --git a/README.md b/README.md
@@ -16,7 +16,7 @@ Browser version is avalible [here](https://realmode.games).
 
 * Intel 8088 or NEC V20 CPU
 * Hardware CPU validator
-* CGA/HGC compatible graphics
+* VGA and CGA compatible graphics
 * GLaBIOS or Turbo XT BIOS 3.1 with extensions
 * Keyboard controller with 83-key XT-style keyboard
 * Serial port with Microsoft 2-button mouse

diff --git a/modules/cga/cga.c b/modules/cga/cga.c
@@ -206,7 +206,7 @@ static void out(struct cga_video *c, vxt_word port, vxt_byte data) {
         case 0x3BF: // Enable HGC.
             // Set bit 0 to enable bit 1 of 3B8.
             // Set bit 1 to enable bit 7 of 3B8 and the second 32k of RAM ("Full" mode).
-            #ifndef VXTU_CGA_NO_HGC
+            #ifndef CGA_NO_HGC
                 c->hgc_enable = data & 3;
             #endif
             break;
@@ -250,7 +250,7 @@ static vxt_error reset(struct cga_video *c) {
 static const char *name(struct cga_video *c) {
     (void)c;
     return "CGA"
-        #ifndef VXTU_CGA_NO_HGC
+        #ifndef CGA_NO_HGC
             "/HGC"
         #endif
         " Compatible Device";

diff --git a/modules/cga/premake5.lua b/modules/cga/premake5.lua
@@ -1,3 +1,7 @@
 files {
     "*.c", "*.h"
 }
+
+-- Make sure to run with no more then 640K
+-- of memory if Hercules mode is enabled.
+defines "CGA_NO_HGC"
diff --git a/modules/vga/font.h b/modules/vga/font.h
diff --git a/modules/vga/premake5.lua b/modules/vga/premake5.lua
@@ -1,6 +1,4 @@
 files {
     "vga.c",
-    "render.inl",
-    "font.h",
-    "palette.h"
-}
+    "render.inl"
+}
diff --git a/modules/vga/render.inl b/modules/vga/render.inl
@@ -35,7 +35,7 @@ static vxt_dword color_lookup(struct snapshot *snap, vxt_byte index) {
 }
 
 static void blit_char(struct vga_video *v, int ch, vxt_byte attr, int x, int y) {
-    struct snapshot *snap = &v->snap;
+    struct snapshot * const snap = &v->snap;
 
     int bg_color_index = (attr & 0x70) >> 4;
 	int fg_color_index = attr & 0xF;
@@ -52,6 +52,9 @@ static void blit_char(struct vga_video *v, int ch, vxt_byte attr, int x, int y)
 
 	vxt_dword bg_color = color_lookup(snap, bg_color_index);
 	vxt_dword fg_color = color_lookup(snap, fg_color_index);
+    int font = (attr & 8) ? snap->font_b : snap->font_a;
+
+    // TODO: Fix this! We only run at 640 in textmode.
     int width = (snap->width >= 640) ? 640 : 320;
     int start = 0;
     int end = 15;
@@ -64,7 +67,7 @@ static void blit_char(struct vga_video *v, int ch, vxt_byte attr, int x, int y)
 
 	for (int i = start; true; i++) {
         int n = i % 16;
-		vxt_byte glyph_line = vga_font[ch * 16 + n];
+		vxt_byte glyph_line = snap->mem[font + ch * 32 + n];
 
 		for (int j = 0; j < 8; j++) {
 			vxt_byte mask = 0x80 >> j;
@@ -85,13 +88,21 @@ static bool snapshot(struct vxt_pirepheral *p) {
 
     memcpy(v->snap.mem, v->mem, MEMORY_SIZE);
     memcpy(v->snap.palette, v->palette, sizeof(v->snap.palette));
-    memcpy(v->snap.pal_reg,  v->reg.attr_reg, 16);
+    memcpy(v->snap.pal_reg, v->reg.attr_reg, 16);
 
     v->snap.width = v->width;
     v->snap.height = v->height;
     v->snap.bpp = v->bpp;
     v->snap.textmode = v->textmode;
 
+    vxt_byte char_map_reg = v->reg.seq_reg[0x3];
+    vxt_byte fa = ((char_map_reg >> 3) & 4) | ((char_map_reg >> 2) & 3);
+    vxt_byte fb = ((char_map_reg >> 2) & 4) | (char_map_reg & 3);
+
+    const int font_offsets[] = { 0x0000, 0x4000, 0x8000, 0xC000, 0x2000, 0x6000, 0xA000, 0xE000 };
+    v->snap.font_a = font_offsets[fa];
+    v->snap.font_b = font_offsets[fb];
+
     v->snap.video_page = ((int)v->reg.crt_reg[0xC] << 8) + (int)v->reg.crt_reg[0xD];
     v->snap.plane_mode = !(v->reg.seq_reg[0x4] & 6);
     v->snap.mode_ctrl = v->reg.attr_reg[0x10];
@@ -110,7 +121,7 @@ static bool snapshot(struct vxt_pirepheral *p) {
 
 static int render(struct vxt_pirepheral *p, int (*f)(int,int,const vxt_byte*,void*), void *userdata) {
     struct vga_video *v = VXT_GET_DEVICE(vga_video, p);
-    struct snapshot *snap = &v->snap;
+    struct snapshot * const snap = &v->snap;
 
     if (snap->textmode) {
         int num_col = (snap->width < 640) ? 40 : 80;

diff --git a/modules/vga/vga.c b/modules/vga/vga.c
@@ -28,11 +28,7 @@ References: https://www.scs.stanford.edu/10wi-cs140/pintos/specs/freevga/vga/vga
 */
 
 #include <vxt/vxtu.h>
-
 #include <frontend.h>
-
-#include "font.h"
-
 #include <string.h>
 
 #define PLANE_SIZE 0x10000
@@ -82,6 +78,8 @@ struct snapshot {
     vxt_word height;
     vxt_byte bpp;
     bool textmode;
+    int font_a;
+    int font_b;
 
     int video_page;
     int pixel_shift;