Beginnings of lo-res graphics

include/apple2.h

@@ -22,6 +22,25 @@ enum color_modes {
     COLOR_FULL,
 };
 
+enum lores_colors {
+    LORES_BLACK,
+    LORES_MAGENTA,
+    LORES_DARKBLUE,
+    LORES_PURPLE,
+    LORES_DARKGREEN,
+    LORES_GRAY1,
+    LORES_MEDBLUE,
+    LORES_LIGHTBLUE,
+    LORES_BROWN,
+    LORES_ORANGE,
+    LORES_GRAY2,
+    LORES_PINK,
+    LORES_LIGHTGREEN,
+    LORES_YELLOW,
+    LORES_AQUAMARINE,
+    LORES_WHITE,
+};
+
 typedef struct {
     /*
      * The apple 2 hardware used an MOS-6502 processor.
@@ -77,5 +96,6 @@ extern int apple2_boot(apple2 *);
 extern void apple2_run_loop(apple2 *);
 extern void apple2_set_color(apple2 *, int);
 extern void apple2_set_video(apple2 *, int);
+extern bool apple2_is_double_video(apple2 *);
 
 #endif

src/apple2.c

@@ -205,3 +205,12 @@ apple2_set_video(apple2 *mach, int mode)
 
     vm_screen_set_logical_coords(mach->screen, width, height);
 }
+
+bool
+apple2_is_double_video(apple2 *mach)
+{
+    return 
+        mach->video_mode == VIDEO_DOUBLE_HIRES ||
+        mach->video_mode == VIDEO_DOUBLE_LORES ||
+        mach->video_mode == VIDEO_80COL_TEXT;
+}

src/apple2.draw.c

@@ -4,11 +4,69 @@
 
 #include "apple2.h"
 
+static int lores_colors[][3] = {
+    { 0x00, 0x00, 0x00 },   // black
+    { 0xff, 0x28, 0x97 },   // magenta
+    { 0x60, 0x4d, 0xbc },   // dark blue
+    { 0xff, 0x44, 0xfd },   // purple
+    { 0x00, 0xa3, 0x60 },   // dark green
+    { 0x9c, 0x9c, 0x9c },   // gray
+    { 0x14, 0xcf, 0xfd },   // medium blue
+    { 0xd0, 0xc3, 0xff },   // light blue
+    { 0x60, 0x72, 0x03 },   // brown
+    { 0xff, 0x6a, 0x3c },   // orange
+    { 0x9c, 0x9c, 0x9c },   // gray
+    { 0xff, 0xa0, 0xd0 },   // pink
+    { 0x14, 0xf5, 0x3c },   // light green
+    { 0xd0, 0xdd, 0x81 },   // yellow
+    { 0x72, 0xff, 0xd0 },   // aquamarine
+    { 0xff, 0xff, 0xff },   // white
+};
+
 void
 apple2_draw_pixel(apple2 *mach, vm_16bit addr)
 {
 }
 
+/*
+ * In single lo-res mode, pixels are 40x40 on the screen. But since our
+ * single mode has 280 pixels that _we_ show, this means that a pixel in
+ * single lo-res is really 7 columns wide. (Confusing yet?) Each "row" in
+ * text page 1 is just a row of visible dots, and 4 rows are equivalent
+ * to one "pixel" in lo-res mode.
+ *
+ * Without text, you get 40x48 pixels.
+ */
+void
+apple2_draw_pixel_lores(apple2 *mach, vm_16bit addr)
+{
+    vm_8bit color = vm_segment_get(mach->memory, addr);
+    vm_8bit top, bottom;
+    SDL_Rect loc;
+    int *colors;
+
+    // The top color is the low order nibble, so we can blank out the
+    // high order nibble by AND-ing a mask of 0x0f (which is b00001111,
+    // 15 decimal). The bottom color, ergo, is the high order nibble;
+    // for that, we simply shift the color 4 positions to the right.
+    top = color & 0x0F;
+    bottom = color >> 4;
+
+    // The next thing we need to consider is where we draw the pixel
+    loc.x = (addr & 0xff) * mach->sysfont->width;
+    loc.y = (addr >> 8) * mach->sysfont->height;
+    loc.w = mach->sysfont->width;
+    loc.h = mach->sysfont->height / 2;
+
+    colors = lores_colors[top];
+    vm_screen_set_color(mach->screen, colors[0], colors[1], colors[2], 255);
+    vm_screen_draw_rect(mach->screen, loc.x, loc.y, loc.w, loc.h); 
+
+    colors = lores_colors[bottom];
+    vm_screen_set_color(mach->screen, colors[0], colors[1], colors[2], 255);
+    vm_screen_draw_rect(mach->screen, loc.x, loc.y + loc.h, loc.w, loc.h);
+}
+
 void
 apple2_draw_text(apple2 *mach, vm_16bit addr)
 {
@@ -25,6 +83,13 @@ apple2_draw_text(apple2 *mach, vm_16bit addr)
         return;
     }
 
+    // If we're updating a page 2 address and we're not in some kind of
+    // double resolution mode, then we shouldn't actually render the
+    // thing.
+    if (addr > 0x07FF && !apple2_is_double_video(mach)) {
+        return;
+    }
+
     // In a given page for 40-column mode, you get 960 grid parts that
     // you may use. In 80-column mode, it's more like 1920 grid parts
     // (40x24 = 960, 80x24 = 1920). The way we look at this is the

tests/apple2.c

@@ -8,7 +8,7 @@ static apple2 *mach;
 void
 setup()
 {
-    mach = apple2_create();
+    mach = apple2_create(700, 480);
 }
 
 void

tests/vm_screen.c

@@ -4,23 +4,18 @@
 
 Test(vm_screen, create) {
     vm_screen *screen;
-    int x = 320;
-    int y = 240;
-    int scale = 2;
 
-    screen = vm_screen_create(x, y, scale);
+    screen = vm_screen_create();
     cr_assert_neq(screen, NULL);
 
-    cr_assert_eq(screen->xcoords, x);
-    cr_assert_eq(screen->ycoords, y);
-    cr_assert_eq(screen->scale, scale);
-
     cr_assert_eq(screen->window, NULL);
     cr_assert_eq(screen->render, NULL);
     cr_assert_eq(screen->rect.x, 0);
     cr_assert_eq(screen->rect.y, 0);
     cr_assert_eq(screen->rect.w, 0);
     cr_assert_eq(screen->rect.h, 0);
+    cr_assert_eq(screen->xcoords, 0);
+    cr_assert_eq(screen->ycoords, 0);
 
     vm_screen_free(screen);
 }