1 files changed, 80 insertions, 5 deletions

diff --git a/src/ppu.c b/src/ppu.c
index 2e0404f..aeb3699 100644
--- a/src/ppu.c
+++ b/src/ppu.c
@@ -1,14 +1,85 @@
 #include "common.h"
+#include "ppu.h"
+
+
+/*
+Copyright (c) 2021 Devine Lu Linvega
+Copyright (c) 2021 Andrew Alderwick
+Copyright (c) 2021 Bad Diode
+
+Permission to use, copy, modify, and distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE.
+*/
+
+#define SCREEN_WIDTH  64 * 8 / 2
+#define SCREEN_HEIGHT 40 * 8 / 2
 
 static u32 *framebuffer = 0;
 
-#define SCREEN_WIDTH  800
-#define SCREEN_HEIGHT 600
+static u32 palette[16];
+static u8 pixels_buf[SCREEN_WIDTH * SCREEN_HEIGHT];
 
-static u32 palette[4];
+static Uint8 blending[5][16] = {
+    {0, 0, 0, 0, 1, 0, 1, 1, 2, 2, 0, 2, 3, 3, 3, 0},
+    {0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3},
+    {1, 2, 3, 1, 1, 2, 3, 1, 1, 2, 3, 1, 1, 2, 3, 1},
+    {2, 3, 1, 2, 2, 3, 1, 2, 2, 3, 1, 2, 2, 3, 1, 2},
+    {1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0}};
 
 void
-ppu_init(void) {
+ppu_pixel(Ppu *p, Uint8 layer, Uint16 x, Uint16 y, Uint8 color)
+{
+    size_t idx = y * p->width + x;
+    Uint8 *pixel = &p->pixels[idx], shift = layer * 2;
+    if(x < p->width && y < p->height) {
+        *pixel = (*pixel & ~(0x3 << shift)) | (color << shift);
+        // framebuffer[idx] = palette[*pixel];
+    }
+}
+
+void
+ppu_1bpp(Ppu *p, Uint8 layer, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy)
+{
+    Uint16 v, h;
+    for(v = 0; v < 8; v++)
+        for(h = 0; h < 8; h++) {
+            Uint8 ch1 = (sprite[v] >> (7 - h)) & 0x1;
+            if(ch1 || blending[4][color])
+                ppu_pixel(p,
+                    layer,
+                    x + (flipx ? 7 - h : h),
+                    y + (flipy ? 7 - v : v),
+                    blending[ch1][color]);
+        }
+}
+
+void
+ppu_2bpp(Ppu *p, Uint8 layer, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy)
+{
+    Uint16 v, h;
+    for(v = 0; v < 8; v++)
+        for(h = 0; h < 8; h++) {
+            Uint8 ch1 = ((sprite[v] >> (7 - h)) & 0x1);
+            Uint8 ch2 = ((sprite[v + 8] >> (7 - h)) & 0x1);
+            Uint8 ch = ch1 + ch2 * 2;
+            if(ch || blending[4][color])
+                ppu_pixel(p,
+                    layer,
+                    x + (flipx ? 7 - h : h),
+                    y + (flipy ? 7 - v : v),
+                    blending[ch][color]);
+        }
+}
+
+int
+ppu_init(Ppu *p, Uint8 hor, Uint8 ver) {
+    p->width = 8 * hor;
+    p->height = 8 * ver;
+
     // Initialize the framebuffer.
     static MboxFramebufferRequest fb_request = {
         .buf_size = 96,
@@ -53,12 +124,16 @@ ppu_init(void) {
         framebuffer = (u32*)((uintptr_t)fb_request.framebuffer_tag.fb_addr);
     } else {
         uart_puts("Unable initialize framebuffer\n");
-        return;
+        return 0;
     }
 
+    p->pixels = pixels_buf;
+
     // Initialize default palette.
     palette[0] = 0x00444444;
     palette[1] = 0x00ffffff;
     palette[2] = 0x007777ff;
     palette[3] = 0x00ff7777;
+
+    return 1;
 }