From b23d52737e669836f7c1847beb64cbc838d6a867 Mon Sep 17 00:00:00 2001
From: Matthew Laux <matthew.laux@gmail.com>
Date: Wed, 20 Jul 2022 22:21:36 -0500
Subject: [PATCH] draw for system 6. it's slow

---
 cli/imgui_example.cpp  |  7 ++--
 src/cpu.c              | 17 ++++++++-
 src/dmg.c              | 40 ++++++++++++++++---
 src/dmg.h              |  1 +
 src/lcd.c              | 15 ++------
 src/lcd.h              |  3 ++
 src/rom.c              |  1 +
 src/rom.h              |  2 +-
 system6/CMakeLists.txt |  2 +
 system6/emulator.c     | 87 ++++++++++++++++++++++++++++++++++--------
 system6/emulator.h     |  8 ----
 system6/lcd_mac.c      |  1 -
 12 files changed, 137 insertions(+), 47 deletions(-)

diff --git a/cli/imgui_example.cpp b/cli/imgui_example.cpp
index ba39374..a2da6e0 100644
--- a/cli/imgui_example.cpp
+++ b/cli/imgui_example.cpp
@@ -54,8 +54,8 @@ GLuint make_output_texture() {
     glGenTextures(1, &image_texture);
     glBindTexture(GL_TEXTURE_2D, image_texture);
 
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 
     return image_texture;
 }
@@ -66,7 +66,8 @@ void convert_output(struct lcd *lcd) {
     for (y = 0; y < 256; y++) {
         for (x = 0; x < 256; x++) {
             int val = lcd->buf[y * 256 + x];
-            int fill = val ? 255 : 0;
+            int fill = 255 - val * 85;
+            //int fill = val ? 255 : 0;
             output_image[out_index++] = fill;
             output_image[out_index++] = fill;
             output_image[out_index++] = fill;
diff --git a/src/cpu.c b/src/cpu.c
index aeae573..5b37d80 100644
--- a/src/cpu.c
+++ b/src/cpu.c
@@ -174,7 +174,16 @@ static u8 shift_right(struct cpu *cpu, u8 value)
 
 static u8 swap(struct cpu *cpu, u8 value)
 {
-    return ((value & 0xf0) >> 4) | ((value & 0x0f) << 4);
+    u8 ret = ((value & 0xf0) >> 4) | ((value & 0x0f) << 4);
+	if(ret == 0) {
+		set_flag(cpu, FLAG_ZERO);
+    } else {
+        clear_flag(cpu, FLAG_ZERO);
+    }
+	clear_flag(cpu, FLAG_SIGN);
+	clear_flag(cpu, FLAG_HALF_CARRY);
+	clear_flag(cpu, FLAG_CARRY);
+    return ret;
 }
 
 static void xor(struct cpu *regs, u8 value)
@@ -634,6 +643,8 @@ void cpu_step(struct cpu *cpu)
             break;
         case 0x2f: // CPL
             cpu->a = ~cpu->a;
+            set_flag(cpu, FLAG_SIGN);
+            set_flag(cpu, FLAG_HALF_CARRY);
             break;
         case 0x31: // LD SP,d16
             cpu->sp = read16(cpu, cpu->pc);
@@ -756,6 +767,10 @@ void cpu_step(struct cpu *cpu)
         case 0xb5: or(cpu, cpu->l); break;
         case 0xb6: or(cpu, read8(cpu, read_hl(cpu))); break;
         case 0xb7: or(cpu, cpu->a); break;
+        case 0xf6:
+            or(cpu, read8(cpu, cpu->pc));
+            cpu->pc++;
+            break;
 
         // CP
         case 0xb8: subtract(cpu, cpu->b, 0, 1); break;
diff --git a/src/dmg.c b/src/dmg.c
index decc845..b7f6bde 100644
--- a/src/dmg.c
+++ b/src/dmg.c
@@ -39,9 +39,18 @@ void dmg_set_button(struct dmg *dmg, int field, int button, int pressed)
 
 static u8 get_button_state(struct dmg *dmg)
 {
-    return dmg->action_selected ? dmg->action_buttons : dmg->joypad;
+    u8 ret = 0;
+    if (dmg->action_selected) {
+        ret |= dmg->action_buttons;
+    }
+    if (dmg->joypad_selected) {
+        ret |= dmg->joypad;
+    }
+    return ret;
 }
 
+static int counter;
+
 u8 dmg_read(void *_dmg, u16 address)
 {
     struct dmg *dmg = (struct dmg *) _dmg;
@@ -66,6 +75,9 @@ u8 dmg_read(void *_dmg, u16 address)
         return dmg->zero_page[address - 0xff80];
     } else if (address == 0xff00) {
         return get_button_state(dmg);
+    } else if (address == 0xff04) {
+        counter++;
+        return counter;
     } else if (address == 0xff0f) {
         return dmg->interrupt_requested;
     } else if (address == 0xffff) {
@@ -93,12 +105,21 @@ void dmg_write(void *_dmg, u16 address, u8 data)
     } else if (address < 0xc000) {
         // TODO switchable ram bank
     } else if (address < 0xe000) {
+        // printf("write ram %04x %02x\n", address, data);
         dmg->main_ram[address - 0xc000] = data;
+    } else if (address == 0xFF46) {
+        u16 src = data << 8;
+        int k = 0;
+        // printf("oam dma %04x\n", src);
+        for (u16 addr = src; addr < src + 0xa0; addr++) {
+            dmg->lcd->oam[k++] = dmg_read(dmg, addr);
+        }
     } else if (lcd_is_valid_addr(address)) {
         lcd_write(dmg->lcd, address, data);
     } else if (address >= 0xff80 && address <= 0xfffe) {
         dmg->zero_page[address - 0xff80] = data;
     } else if (address == 0xff00) {
+        dmg->joypad_selected = data & (1 << 4);
         dmg->action_selected = data & (1 << 5);
     } else if (address == 0xff0f) {
         dmg->interrupt_requested = data;
@@ -126,9 +147,19 @@ void dmg_step(void *_dmg)
     if (dmg->cpu->cycle_count - dmg->last_lcd_update >= 456) {
         dmg->last_lcd_update = dmg->cpu->cycle_count;
         int next_scanline = lcd_step(dmg->lcd);
+
+        // update LYC
+        if (next_scanline == lcd_read(dmg->lcd, REG_LYC)) {
+            lcd_set_bit(dmg->lcd, REG_STAT, STAT_FLAG_MATCH);
+            dmg_request_interrupt(dmg, INT_LCDSTAT);
+        } else {
+            lcd_clear_bit(dmg->lcd, REG_STAT, STAT_FLAG_MATCH);
+        }
+
         if (next_scanline == 144) {
             // vblank has started, draw all the stuff from ram into the lcd
             dmg_request_interrupt(dmg, INT_VBLANK);
+            dmg_request_interrupt(dmg, INT_SERIAL);
 
             int lcdc = lcd_read(dmg->lcd, REG_LCDC);
             int bg_base = (lcdc & LCDC_BG_TILE_MAP) ? 0x9c00 : 0x9800;
@@ -136,7 +167,7 @@ void dmg_step(void *_dmg)
             int use_unsigned = lcdc & LCDC_BG_TILE_DATA;
             int tilebase = use_unsigned ? 0x8000 : 0x9000;
 
-            printf("%04x %04x %04x\n", bg_base, window_base, tilebase);
+            //printf("%04x %04x %04x\n", bg_base, window_base, tilebase);
 
             int k = 0, off = 0;
             int tile_y = 0, tile_x = 0;
@@ -155,9 +186,8 @@ void dmg_step(void *_dmg)
                         int data1 = dmg_read(dmg, eff_addr + b);
                         int data2 = dmg_read(dmg, eff_addr + b + 1);
                         for (i = 7; i >= 0; i--) {
-                            // monochrome for now
-                            dmg->lcd->buf[off] = (data1 & (1 << i)) ? 1 : 0;
-                            //dmg->lcd->buf[off] |= (data2 & (1 << i)) ? 1 : 0;
+                            dmg->lcd->buf[off] = ((data1 & (1 << i)) ? 1 : 0);// << 1;
+                            //dmg->lcd->buf[off] |= (data1 & (1 << i)) ? 1 : 0;
                             off++;
                         }
                         off += 248;
diff --git a/src/dmg.h b/src/dmg.h
index ca48da2..2ae02b0 100644
--- a/src/dmg.h
+++ b/src/dmg.h
@@ -25,6 +25,7 @@ struct dmg {
     u8 video_ram[0x2000];
     u8 zero_page[0x80];
     u32 last_lcd_update;
+    int joypad_selected;
     int action_selected; // non-0 if A/B/start/select selected, 0 for directions
     u8 interrupt_enabled;
     u8 interrupt_requested;
diff --git a/src/lcd.c b/src/lcd.c
index 85f8afe..c2a7a1d 100644
--- a/src/lcd.c
+++ b/src/lcd.c
@@ -5,12 +5,12 @@
 #include "types.h"
 #include "lcd.h"
 
-static void set_bit(struct lcd *lcd, u16 addr, u8 bit)
+void lcd_set_bit(struct lcd *lcd, u16 addr, u8 bit)
 {
     lcd_write(lcd, addr, lcd_read(lcd, addr) | (1 << bit));
 }
 
-static void clear_bit(struct lcd *lcd, u16 addr, u8 bit)
+void lcd_clear_bit(struct lcd *lcd, u16 addr, u8 bit)
 {
     lcd_write(lcd, addr, lcd_read(lcd, addr) & ~(1 << bit));
 }
@@ -18,6 +18,7 @@ static void clear_bit(struct lcd *lcd, u16 addr, u8 bit)
 void lcd_new(struct lcd *lcd)
 {
     lcd->buf = malloc(256 * 256);
+    memset(lcd->buf, 0, 256 * 256);
     // todo < 8 bpp
     lcd->pixels = malloc(LCD_WIDTH * LCD_HEIGHT);
 }
@@ -41,9 +42,6 @@ void lcd_write(struct lcd *lcd, u16 addr, u8 value)
         lcd->oam[addr - 0xfe00] = value;
     } else {
         lcd->regs[addr - REG_LCD_BASE] = value;
-        if (addr == 0xFF46) {
-            // OAM DMA
-        }
     }
 }
 
@@ -64,13 +62,6 @@ void lcd_copy(struct lcd *lcd)
 
 int lcd_step(struct lcd *lcd)
 {
-    // update LYC
-    if (lcd_read(lcd, REG_LY) == lcd_read(lcd, REG_LYC)) {
-        set_bit(lcd, REG_STAT, STAT_FLAG_MATCH);
-    } else {
-        clear_bit(lcd, REG_STAT, STAT_FLAG_MATCH);
-    }
-
     // step to next scanline 0-153
     u8 next_scanline = (lcd_read(lcd, REG_LY) + 1) % 154;
     lcd_write(lcd, REG_LY, next_scanline);
diff --git a/src/lcd.h b/src/lcd.h
index 3562645..cb9e9b4 100644
--- a/src/lcd.h
+++ b/src/lcd.h
@@ -48,6 +48,9 @@ void lcd_write(struct lcd *lcd, u16 addr, u8 value);
 
 void lcd_put_pixel(struct lcd *lcd, u8 x, u8 y, u8 value);
 
+void lcd_set_bit(struct lcd *lcd, u16 addr, u8 bit);
+void lcd_clear_bit(struct lcd *lcd, u16 addr, u8 bit);
+
 // i feel like i'm going to need to call this every cycle and update regs
 int lcd_step(struct lcd *lcd);
 void lcd_copy(struct lcd *lcd);
diff --git a/src/rom.c b/src/rom.c
index 7eaa1e2..86b4349 100644
--- a/src/rom.c
+++ b/src/rom.c
@@ -19,6 +19,7 @@ int rom_load(struct rom *rom, const char *filename)
 
     rom->type = 0; // TODO read type from cart
     rom->data = malloc(len);
+    rom->length = len;
     if (fread(rom->data, 1, len, fp) < len) {
         return 0;
     }
diff --git a/src/rom.h b/src/rom.h
index 97e1cfc..4bcb1f5 100644
--- a/src/rom.h
+++ b/src/rom.h
@@ -4,11 +4,11 @@
 #include "types.h"
 
 struct rom {
+    u32 length;
     int type;
     u8 *data;
 };
 
-
 int rom_load(struct rom *rom, const char *filename);
 
 void rom_free(struct rom *rom);
diff --git a/system6/CMakeLists.txt b/system6/CMakeLists.txt
index 7b54d41..b757930 100644
--- a/system6/CMakeLists.txt
+++ b/system6/CMakeLists.txt
@@ -3,6 +3,8 @@ cmake_minimum_required(VERSION 3.9)
 
 include_directories(../src)
 
+set(CMAKE_CXX_FLAGS "-O3")
+
 add_application(Emulator
     ../src/bootstrap.c
     ../src/cpu.c
diff --git a/system6/emulator.c b/system6/emulator.c
index 63c6268..fc724ea 100644
--- a/system6/emulator.c
+++ b/system6/emulator.c
@@ -17,14 +17,24 @@
 
 #include "emulator.h"
 
+#include "dmg.h"
+#include "cpu.h"
+#include "rom.h"
+#include "lcd.h"
+
 WindowPtr g_wp;
+DialogPtr stateDialog;
 unsigned char g_running;
+unsigned char emulationOn;
 
 static Point windowPt = { WINDOW_Y, WINDOW_X };
 
 static Rect windowBounds = { WINDOW_Y, WINDOW_X, WINDOW_Y + WINDOW_HEIGHT, WINDOW_X + WINDOW_WIDTH };
 
-emu_state theState;
+struct cpu cpu;
+struct rom rom;
+struct lcd lcd;
+struct dmg dmg;
 
 void InitEverything(void)
 {	
@@ -45,10 +55,35 @@ void InitEverything(void)
   g_running = 1;
 }
 
+char offscreen[32 * 256];
+Rect offscreenRect = { 0, 0, 256, 256 };
+
+BitMap offscreenBmp;
+
+int lastTicks;
+
 void Render(void)
 {
-  MoveTo(10, 10);
-  DrawString("\pTest 123");
+  long k = 0, dst;
+  for (dst = 0; dst < 32 * 256; dst++) {
+    offscreen[dst] = lcd.buf[k++] << 7
+            | lcd.buf[k++] << 6
+            | lcd.buf[k++] << 5
+            | lcd.buf[k++] << 4
+            | lcd.buf[k++] << 3
+            | lcd.buf[k++] << 2
+            | lcd.buf[k++] << 1
+            | lcd.buf[k++];
+  }
+  SetPort(g_wp);
+  CopyBits(&offscreenBmp, &g_wp->portBits, &offscreenRect, &g_wp->portRect, srcCopy, NULL);
+
+  //EraseRect(&g_wp->portRect);
+  MoveTo(10, 160);
+  char debug[128];
+  sprintf(debug, "PC: %04x", cpu.pc);
+  C2PStr(debug);
+  DrawString(debug);
 }
 
 void StartEmulation(void)
@@ -57,7 +92,10 @@ void StartEmulation(void)
         noGrowDocProc, (WindowPtr) -1, true, 0);
   SetPort(g_wp);
 
-  
+  offscreenBmp.baseAddr = offscreen;
+  offscreenBmp.bounds = offscreenRect;
+  offscreenBmp.rowBytes = 32;
+  emulationOn = 1;
 }
 
 bool LoadRom(StrFileName fileName, short vRefNum)
@@ -66,12 +104,11 @@ bool LoadRom(StrFileName fileName, short vRefNum)
   short fileNo;
   long amtRead;
   
-  if(theState.rom != NULL) {
+  if(rom.data != NULL) {
     // unload existing ROM
-    free((char *) theState.rom);
-    theState.romLength = 0;
+    free((char *) rom.data);
+    rom.length = 0;
   }
-  
 
   err = FSOpen(fileName, vRefNum, &fileNo);
   
@@ -79,16 +116,16 @@ bool LoadRom(StrFileName fileName, short vRefNum)
     return false;
   }
   
-  GetEOF(fileNo, (long *) &theState.romLength);
-  theState.rom = (unsigned char *) malloc(theState.romLength);
-  if(theState.rom == NULL) {
+  GetEOF(fileNo, (long *) &rom.length);
+  rom.data = (unsigned char *) malloc(rom.length);
+  if(rom.data == NULL) {
     Alert(ALRT_NOT_ENOUGH_RAM, NULL);
     return false;
   }
   
-  amtRead = theState.romLength;
+  amtRead = rom.length;
   
-  FSRead(fileNo, &amtRead, theState.rom);
+  FSRead(fileNo, &amtRead, rom.data);
   return true;
 }
 
@@ -112,7 +149,6 @@ bool ShowOpenBox(void)
   return false;
 }
 
-DialogPtr stateDialog;
 void ShowStateDialog(void)
 {
   DialogPtr dp;
@@ -207,15 +243,34 @@ void OnMouseDown(EventRecord *pEvt)
 }
 
 // -- ENTRY POINT --
-
 int main(int argc, char *argv[])
 {
   EventRecord evt;
+
+  int executed;
+  int paused = 0;
+  int pause_next = 0;
   
   InitEverything();
+
+  lcd_new(&lcd);
+  dmg_new(&dmg, &cpu, &rom, &lcd);
+  cpu_bind_mem_model(&cpu, &dmg, dmg_read, dmg_write);
+
+  cpu.pc = 0x100;
   
+  int start = TickCount();
   while(g_running) {
-    if(WaitNextEvent(everyEvent, &evt, 10, 0) != nullEvent) {
+    if (emulationOn) {
+        dmg_step(&dmg);
+        int now = TickCount();
+        if (now > lastTicks + 100) {
+          lastTicks = now;
+          Render();
+        }
+    }
+
+    if(WaitNextEvent(everyEvent, &evt, 0, 0) != nullEvent) {
       if (IsDialogEvent(&evt)) {
         DialogRef hitBox;
         DialogItemIndex hitItem;
diff --git a/system6/emulator.h b/system6/emulator.h
index 38a7b33..effbe82 100644
--- a/system6/emulator.h
+++ b/system6/emulator.h
@@ -44,12 +44,4 @@ typedef unsigned char bool;
 #define true 1
 #define false 0
 
-typedef struct _emu_state {
-	struct dmg *cpu;
-	u8 *rom;
-	unsigned long int romLength;
-} emu_state;
-
-extern emu_state theState;
-
 #endif
\ No newline at end of file
diff --git a/system6/lcd_mac.c b/system6/lcd_mac.c
index cc15a41..388aea5 100644
--- a/system6/lcd_mac.c
+++ b/system6/lcd_mac.c
@@ -4,4 +4,3 @@ void lcd_draw(struct lcd *lcd)
 {
 
 }
-