Add initial PPU implementation for UXN

3 files changed, 156 insertions, 78 deletions

diff --git a/src/main.c b/src/main.c
index f2ffa5b..fc073c9 100644
--- a/src/main.c
+++ b/src/main.c
@@ -4,6 +4,7 @@
 #include "rom.c"
 
 static Uxn u;
+static Ppu ppu;
 static Device *devscreen;
 static Device *devctrl;
 static Device *devmouse;
@@ -24,6 +25,8 @@ console_talk(Device *d, u8 b0, u8 w) {
     }
     switch(b0) {
         case 0x8: stmp[0] = d->dat[0x8]; stmp[1] = 0; uart_puts(stmp); break;
+        // TODO: implement printf for the uart to be able to format
+        // numbers.
         // case 0x9: txt_printf("0x%02x", d->dat[0x9]); break;
         // case 0xb: txt_printf("0x%04x", mempeek16(d->dat, 0xa)); break;
         // case 0xd: txt_printf("%s", &d->mem[mempeek16(d->dat, 0xc)]); break;
@@ -32,72 +35,55 @@ console_talk(Device *d, u8 b0, u8 w) {
 
 static void
 docolors(Device *d) {
-        for(size_t i = 0; i < 4; ++i) {
-                u8 r = ((d->dat[0x8 + i / 2] >> (!(i % 2) << 2)) & 0x0f) * 0x11;
-                u8 g = ((d->dat[0xa + i / 2] >> (!(i % 2) << 2)) & 0x0f) * 0x11;
-                u8 b = ((d->dat[0xc + i / 2] >> (!(i % 2) << 2)) & 0x0f) * 0x11;
-                palette[i] = (b << 16) | (g << 8) | r;
-        }
+    for(size_t i = 0; i < 4; ++i) {
+        u8 r = ((d->dat[0x8 + i / 2] >> (!(i % 2) << 2)) & 0x0f) * 0x11;
+        u8 g = ((d->dat[0xa + i / 2] >> (!(i % 2) << 2)) & 0x0f) * 0x11;
+        u8 b = ((d->dat[0xc + i / 2] >> (!(i % 2) << 2)) & 0x0f) * 0x11;
+        palette[i] = (b << 16) | (g << 8) | r;
+    }
+    for(size_t i = 4; i < 16; ++i) {
+        palette[i] = palette[i / 4];
+    }
 }
 
 void
 system_talk(Device *d, u8 b0, u8 w) {
-    // uart_puts("system_talk\n");
-    // TODO: Implement...
-        if(!w) { /* read */
-                switch(b0) {
-                case 0x2: d->dat[0x2] = d->u->wst.ptr; break;
-                case 0x3: d->dat[0x3] = d->u->rst.ptr; break;
-                }
-        } else { /* write */
-                switch(b0) {
-                case 0x2: d->u->wst.ptr = d->dat[0x2]; break;
-                case 0x3: d->u->rst.ptr = d->dat[0x3]; break;
-                case 0xf: d->u->ram.ptr = 0x0000; break;
-                }
-                if(b0 > 0x7 && b0 < 0xe) {
-                        docolors(d);
+    if(!w) { /* read */
+        switch(b0) {
+        case 0x2: d->dat[0x2] = d->u->wst.ptr; break;
+        case 0x3: d->dat[0x3] = d->u->rst.ptr; break;
+        }
+    } else { /* write */
+        switch(b0) {
+        case 0x2: d->u->wst.ptr = d->dat[0x2]; break;
+        case 0x3: d->u->rst.ptr = d->dat[0x3]; break;
+        case 0xf: d->u->ram.ptr = 0x0000; break;
         }
-        }
+        if(b0 > 0x7 && b0 < 0xe) {
+            docolors(d);
+        }
+    }
     (void)b0;
 }
 
 void
 screen_talk(Device *d, u8 b0, u8 w) {
     // uart_puts("screen_talk\n");
-    // TODO: Implement...
-    // if(w && b0 == 0xe) {
-    //     u16 x = mempeek16(d->dat, 0x8);
-    //     u16 y = mempeek16(d->dat, 0xa);
-    //     u8 *addr = &d->mem[mempeek16(d->dat, 0xc)];
-    //     u8 *layer = d->dat[0xe] >> 4 & 0x1 ? ppu.fg : ppu.bg;
-    //     u8 mode = d->dat[0xe] >> 5;
-    //     u8 color = d->dat[0xf] & 0xf;
-    //     if(!mode) {
-    //         ppu_pixel(layer, x, y, d->dat[0xe] & 0x3);
-    //     } else if(mode-- & 0x1) {
-    //         u8 flipx = mode & 0x2;
-    //         u8 flipy = mode & 0x4;
-    //         ppu_1bpp(layer, x, y, addr, color, flipx, flipy);
-    //     } else {
-    //         u8 flipx = mode & 0x2;
-    //         u8 flipy = mode & 0x4;
-    //         ppu_2bpp(layer, x, y, addr, color, flipx, flipy);
-    //     }
-    // } else if(w && b0 == 0xf) {
-    //     u16 x = mempeek16(d->dat, 0x8);
-    //     u16 y = mempeek16(d->dat, 0xa);
-    //     u8 *addr = &d->mem[mempeek16(d->dat, 0xc)];
-    //     u8 *layer = d->dat[0xf] >> 6 & 0x1 ? ppu.fg : ppu.bg;
-    //     u8 color = d->dat[0xf] & 0xf;
-    //     u8 flipx = (d->dat[0xf] >> 0x4) & 0x1;
-    //     u8 flipy = (d->dat[0xf] >> 0x5) & 0x1;
-    //     if(d->dat[0xf] >> 0x7 & 0x1) {
-    //         ppu_2bpp(layer, x, y, addr, color, flipx, flipy);
-    //     } else {
-    //         ppu_1bpp(layer, x, y, addr, color, flipx, flipy);
-    //     }
-    // }
+    if(w && b0 == 0xe) {
+        Uint16 x = mempeek16(d->dat, 0x8);
+        Uint16 y = mempeek16(d->dat, 0xa);
+        Uint8 layer = d->dat[0xe] >> 4 & 0x1;
+        ppu_pixel(&ppu, layer, x, y, d->dat[0xe] & 0x3);
+    } else if(w && b0 == 0xf) {
+        Uint16 x = mempeek16(d->dat, 0x8);
+        Uint16 y = mempeek16(d->dat, 0xa);
+        Uint8 layer = d->dat[0xf] >> 0x6 & 0x1;
+        Uint8 *addr = &d->mem[mempeek16(d->dat, 0xc)];
+        if(d->dat[0xf] >> 0x7 & 0x1)
+            ppu_2bpp(&ppu, layer, x, y, addr, d->dat[0xf] & 0xf, d->dat[0xf] >> 0x4 & 0x1, d->dat[0xf] >> 0x5 & 0x1);
+        else
+            ppu_1bpp(&ppu, layer, x, y, addr, d->dat[0xf] & 0xf, d->dat[0xf] >> 0x4 & 0x1, d->dat[0xf] >> 0x5 & 0x1);
+    }
 }
 
 static void
@@ -111,8 +97,8 @@ audio_talk(Device *d, u8 b0, u8 w) {
 
 void
 datetime_talk(Device *d, u8 b0, u8 w) {
-    // uart_puts("datetime_talk\n");
     // TODO: Implement...
+    // uart_puts("datetime_talk\n");
     (void)d;
     (void)b0;
     (void)w;
@@ -120,8 +106,8 @@ datetime_talk(Device *d, u8 b0, u8 w) {
 
 void
 file_talk(Device *d, u8 b0, u8 w) {
-    // uart_puts("file_talk\n");
     // TODO: Implement...
+    // uart_puts("file_talk\n");
     (void)d;
     (void)b0;
     (void)w;
@@ -131,7 +117,7 @@ void
 init_uxn() {
     uart_puts("Initializing UXN.\n");
     uart_init();
-    ppu_init();
+    ppu_init(&ppu, SCREEN_WIDTH / 8,  SCREEN_HEIGHT / 8);
 
     // Copy rom to VM.
     memcpy(u.ram.dat + PAGE_PROGRAM, uxn_rom, sizeof(uxn_rom));
@@ -153,8 +139,8 @@ init_uxn() {
     uxn_port(&u, 0xd, "---", nil_talk);
     uxn_port(&u, 0xe, "---", nil_talk);
     uxn_port(&u, 0xf, "---", nil_talk);
-    // mempoke16(devscreen->dat, 2, ppu.hor * 8);
-    // mempoke16(devscreen->dat, 4, ppu.ver * 8);
+    mempoke16(devscreen->dat, 2, ppu.width);
+    mempoke16(devscreen->dat, 4, ppu.height);
 }
 
 void main(void) {
@@ -166,19 +152,11 @@ void main(void) {
         // Echo input to standard output.
         uxn_eval(&u, mempeek16(devscreen->dat, 0));
 
-        // DEBUG: testing fb drawing.
-        u32 lines = SCREEN_WIDTH * SCREEN_HEIGHT / 4;
-        for (size_t i = 0; i < lines; i++) {
-            framebuffer[i] = palette[0];
-        }
-        for (size_t i = lines; i < lines * 2; i++) {
-            framebuffer[i] = palette[1];
-        }
-        for (size_t i = lines * 2; i < lines * 3; i++) {
-            framebuffer[i] = palette[2];
-        }
-        for (size_t i = lines * 3; i < lines * 4; i++) {
-            framebuffer[i] = palette[3];
+        // Blit ppu.pixels to the framebuffer.
+        // NOTE: This is very inefficient, we likely want to keep track of the
+        // lines/tiles that have changed and only copy those.
+        for (size_t i = 0; i < SCREEN_WIDTH * SCREEN_HEIGHT; i++) {
+            framebuffer[i] = palette[ppu.pixels[i]];
         }
     }
 }
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;
 }
diff --git a/src/ppu.h b/src/ppu.h
new file mode 100644
index 0000000..45af70b
--- /dev/null
+++ b/src/ppu.h
@@ -0,0 +1,25 @@
+/*
+Copyright (c) 2021 Devine Lu Linvega
+Copyright (c) 2021 Andrew Alderwick
+
+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.
+*/
+
+typedef unsigned char Uint8;
+typedef unsigned short Uint16;
+typedef unsigned int Uint32;
+
+typedef struct Ppu {
+        Uint16 width, height;
+        Uint8 *pixels;
+} Ppu;
+
+int ppu_init(Ppu *p, Uint8 hor, Uint8 ver);
+void ppu_pixel(Ppu *p, Uint8 layer, Uint16 x, Uint16 y, Uint8 color);
+void ppu_1bpp(Ppu *p, Uint8 layer, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy);
+void ppu_2bpp(Ppu *p, Uint8 layer, Uint16 x, Uint16 y, Uint8 *sprite, Uint8 color, Uint8 flipx, Uint8 flipy);