add vram tile viewer thing

cli/CMakeLists.txt

@@ -11,7 +11,7 @@ execute_process(COMMAND sdl2-config --libs
                 OUTPUT_VARIABLE SDL_LIBS 
                 OUTPUT_STRIP_TRAILING_WHITESPACE)
 
-set(CMAKE_CXX_FLAGS "-std=c++14 ${SDL_CFLAGS}")
+set(CMAKE_CXX_FLAGS "-std=c++14 -g -DGB6_DEBUG ${SDL_CFLAGS}")
 
 add_executable(gb6
     ../src/bootstrap.c

cli/imgui_example.cpp

@@ -9,6 +9,7 @@
 #include "imgui/imgui_memory_editor.h"
 #include <stdio.h>
 #include <SDL.h>
+#include <SDL_timer.h>
 #if defined(IMGUI_IMPL_OPENGL_ES2)
 #include <SDL_opengles2.h>
 #else
@@ -49,6 +50,7 @@ GLuint make_output_texture() {
 }
 
 unsigned char output_image[256 * 256 * 4];
+unsigned char vram_tiles[256 * 96 * 4];
 
 void convert_output(struct lcd *lcd) {
     int x, y;
@@ -57,14 +59,41 @@ void convert_output(struct lcd *lcd) {
         for (x = 0; x < 256; x++) {
             int val = lcd->buf[y * 256 + x];
             int fill = val ? 255 : 0;
-            output_image[out_index++] = val;
+            output_image[out_index++] = fill;
-            output_image[out_index++] = val;
+            output_image[out_index++] = fill;
-            output_image[out_index++] = val;
+            output_image[out_index++] = fill;
             output_image[out_index++] = 255;
         }
     }
 }
 
+void convert_vram(struct dmg *dmg) {
+    int tile_y, tile_x;
+    int off, in;
+    for (tile_y = 0; tile_y < 12; tile_y++) {
+        for (tile_x = 0; tile_x < 32; tile_x++) {
+            off = 256 * 8 * tile_y + 8 * tile_x;
+            in = 16 * (tile_y * 32 + tile_x);
+            int b, i;
+            for (b = 0; b < 16; b += 2) {
+                int data1 = dmg->video_ram[in + b];
+                int data2 = dmg->video_ram[in + b + 1];
+                for (i = 7; i >= 0; i--) {
+                    // monochrome for now
+                    int fill = (data1 & (1 << i)) ? 255 : 0;
+                    vram_tiles[4 * off + 0] = fill;
+                    vram_tiles[4 * off + 1] = fill;
+                    vram_tiles[4 * off + 2] = fill;
+                    vram_tiles[4 * off + 3] = 255;
+                    //dmg->lcd->buf[off] |= (data2 & (1 << i)) ? 1 : 0;
+                    off++;
+                }
+                off += 248;
+            }
+        }
+    }
+}
+
 char full_address_space[0x10000];
 void fill_memory_editor(struct dmg *dmg)
 {
@@ -164,6 +193,7 @@ int main(int argc, char *argv[])
 
     // setup output
     GLuint texture = make_output_texture();
+    GLuint vram_texture = make_output_texture();
 
     // Our state
     bool z_flag = false;
@@ -173,8 +203,13 @@ int main(int argc, char *argv[])
 
     // Main loop
     bool done = false;
+    unsigned int lastDrawTime = 0, currentTime;
     while (!done)
     {
+        dmg_step(&dmg);
+
+        currentTime = SDL_GetTicks();
+        if (currentTime >= lastDrawTime + 16) {
             // Poll and handle events (inputs, window resize, etc.)
             // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
             // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
@@ -195,8 +230,6 @@ int main(int argc, char *argv[])
             ImGui_ImplSDL2_NewFrame();
             ImGui::NewFrame();
 
-        dmg_step(&dmg);
-
             z_flag = flag_isset(dmg.cpu, FLAG_ZERO);
             n_flag = flag_isset(dmg.cpu, FLAG_SIGN);
             h_flag = flag_isset(dmg.cpu, FLAG_HALF_CARRY);
@@ -243,10 +276,20 @@ int main(int argc, char *argv[])
                 ImGui::End();
             }
 
+            {
+                ImGui::Begin("VRAM");
+
+                convert_vram(&dmg);
+                glBindTexture(GL_TEXTURE_2D, vram_texture);
+                glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 256, 96, 0, GL_RGBA, GL_UNSIGNED_BYTE, vram_tiles);
+                ImGui::Image((void*)(intptr_t) vram_texture, ImVec2(256, 96));
+
+                ImGui::End();
+            }
+
             fill_memory_editor(&dmg);
 
             editor.DrawWindow("Memory", full_address_space, 0x10000, 0x0000);
-        editor.DrawWindow("LCD", dmg.lcd->buf, 0x2000, 0);
 
             // Rendering
             ImGui::Render();
@@ -255,6 +298,9 @@ int main(int argc, char *argv[])
             glClear(GL_COLOR_BUFFER_BIT);
             ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
             SDL_GL_SwapWindow(window);
+
+            lastDrawTime = currentTime;
+        }
     }
 
     rom_free(&rom);

src/cpu.c

@@ -110,23 +110,53 @@ static void dec_with_carry(struct cpu *regs, u8 *reg)
 
 static u8 rotate_left(struct cpu *regs, u8 reg)
 {
-	// copy old leftmost bit to carry flag
+    int old_carry = flag_isset(regs, FLAG_CARRY);
-	regs->f = (reg & 0x80) >> 3 | (regs->f & ~FLAG_CARRY);
+	// copy old leftmost bit to carry flag, clear Z, N, H
+	regs->f = (reg & 0x80) >> 3;
 	// rotate
-	int result = reg << 1;
+	int result = reg << 1 | old_carry;
-	// restore leftmost (now rightmost) bit
+    if (!result) set_flag(regs, FLAG_ZERO);
-	result |= (regs->f & FLAG_CARRY) >> 4;
+    return result;
+}
+
+static u8 rlc(struct cpu *cpu, u8 val)
+{
+    int old_msb = (val & 0x80) >> 7;
+    int result = (val & 0x7f) << 1 | old_msb;
+    if (!result)
+        set_flag(cpu, FLAG_ZERO);
+    else clear_flag(cpu, FLAG_ZERO);
+    clear_flag(cpu, FLAG_SIGN);
+    clear_flag(cpu, FLAG_HALF_CARRY);
+    if (old_msb) 
+        set_flag(cpu, FLAG_CARRY);
+    else clear_flag(cpu, FLAG_CARRY);
     return result;
 }
 
 static u8 rotate_right(struct cpu *regs, u8 reg)
 {
-	// copy old rightmost bit to carry flag
+    int old_carry = flag_isset(regs, FLAG_CARRY) << 7;
-	regs->f = (reg & 0x01) << 4 | (regs->f & ~FLAG_CARRY);
+	// copy old rightmost bit to carry flag, clear ZNH
+	regs->f = (reg & 0x01) << 4;
 	// rotate
-	int result = reg >> 1;
+	int result = old_carry | reg >> 1;
-	// restore rightmost bit to left
+    if (!result) set_flag(regs, FLAG_ZERO);
-	result |= (regs->f & FLAG_CARRY) << 3;
+    return result;
+}
+
+static u8 rrc(struct cpu *cpu, u8 val)
+{
+    int old_lsb = (val & 1) << 7;
+    int result = old_lsb | (val & 0xfe) >> 1;
+    if (!result)
+        set_flag(cpu, FLAG_ZERO);
+    else clear_flag(cpu, FLAG_ZERO);
+    clear_flag(cpu, FLAG_SIGN);
+    clear_flag(cpu, FLAG_HALF_CARRY);
+    if (old_lsb) 
+        set_flag(cpu, FLAG_CARRY);
+    else clear_flag(cpu, FLAG_CARRY);
     return result;
 }
 
@@ -202,10 +232,18 @@ static void subtract(struct cpu *cpu, u8 value, int with_carry, int just_compare
     if (with_carry && flag_isset(cpu, FLAG_CARRY)) {
         sum_full--;
     }
-    sum_trunc = (u8) sum_full;
+    sum_trunc = (u8) (sum_full & 0xff);
-    set_flag(cpu, sum_trunc == 0 ? FLAG_ZERO : 0);
+    if (!sum_trunc) {
+        set_flag(cpu, FLAG_ZERO);
+    } else {
+        clear_flag(cpu, FLAG_ZERO);
+    }
     set_flag(cpu, FLAG_SIGN);
-    set_flag(cpu, sum_full < sum_trunc ? FLAG_CARRY : 0);
+    if (sum_full < sum_trunc) {
+        set_flag(cpu, FLAG_CARRY);
+    } else {
+        clear_flag(cpu, FLAG_CARRY);
+    }
     // TODO H
 
     if (!just_compare) {
@@ -296,10 +334,10 @@ static void extended_insn(struct cpu *cpu, u8 insn)
     int reg = insn & 0x7;
 
     u8 (*funcs[8])(struct cpu *, u8) = {
+        rlc,
+        rrc,
         rotate_left,
         rotate_right,
-        rotate_left, // TODO non-carry version
-        rotate_right,
         shift_left,
         shift_right,
         swap,
@@ -356,7 +394,7 @@ void cpu_step(struct cpu *cpu)
             cpu->pc += 2;
             break;
         case 0x07: // RLCA
-            cpu->a = rotate_left(cpu, cpu->a);
+            cpu->a = rlc(cpu, cpu->a);
             break;
         case 0x08: // LD (a16),SP
             write16(cpu, read16(cpu, cpu->pc), cpu->sp);
@@ -544,6 +582,7 @@ void cpu_step(struct cpu *cpu)
         case 0xc0: // RET NZ
             if (!flag_isset(cpu, FLAG_ZERO)) {
                 cpu->pc = pop(cpu);
+                cpu->cycle_count += instructions[opc].cycles_branch - instructions[opc].cycles;
             }
             break;
         case 0xc9: // RET
@@ -561,6 +600,7 @@ void cpu_step(struct cpu *cpu)
         case 0xd2: // JP NC,a16
             if (flag_isset(cpu, FLAG_CARRY)) {
                 cpu->pc = read16(cpu, cpu->pc);
+                cpu->cycle_count += instructions[opc].cycles_branch - instructions[opc].cycles;
             }
             break;
 
@@ -657,6 +697,18 @@ void cpu_step(struct cpu *cpu)
         case 0xc5: // PUSH BC
             push(cpu, read_bc(cpu));
             break;
+        case 0xc8: // RET Z
+            if (flag_isset(cpu, FLAG_ZERO)) {
+                cpu->pc = pop(cpu);
+                cpu->cycle_count += instructions[opc].cycles_branch - instructions[opc].cycles;
+            }
+            break;
+        case 0xca: // JP Z, u16
+            if (flag_isset(cpu, FLAG_ZERO)) {
+                cpu->pc = read16(cpu, cpu->pc);
+                cpu->cycle_count += instructions[opc].cycles_branch - instructions[opc].cycles;
+            }
+            break;
         case 0xcb:
             extended_insn(cpu, read8(cpu, cpu->pc));
             cpu->pc++;
@@ -665,13 +717,28 @@ void cpu_step(struct cpu *cpu)
             add(cpu, read8(cpu, cpu->pc), 1);
             cpu->pc++;
             break;
+        case 0xd1: // POP DE
+            write_de(cpu, pop(cpu));
+            break;
+        case 0xd5: // PUSH DE
+            push(cpu, read_de(cpu));
+            break;
         case 0xe0: // LD (a8),A
             write8(cpu, 0xff00 + read8(cpu, cpu->pc), cpu->a);
             cpu->pc++;
             break;
+        case 0xe1: // POP HL
+            write_hl(cpu, pop(cpu));
+            break;
         case 0xe2: // LD (C),A
             write8(cpu, 0xff00 + cpu->c, cpu->a);
             break;
+        case 0xe5: // PUSH HL
+            push(cpu, read_hl(cpu));
+            break;
+        case 0xe9: // JP HL
+            cpu->pc = read_hl(cpu);
+            break;
         case 0xea: // LD (a16),A
             write8(cpu, read16(cpu, cpu->pc), cpu->a);
             cpu->pc += 2;
@@ -680,11 +747,21 @@ void cpu_step(struct cpu *cpu)
             cpu->a = read8(cpu, 0xff00 + read8(cpu, cpu->pc));
             cpu->pc++;
             break;
+        case 0xf1: // POP AF
+            write_af(cpu, pop(cpu));
+            break;
         case 0xf2: // LD A,(C)
             cpu->a = read8(cpu, 0xff00 + cpu->c);
             break;
         case 0xf3: // DI
             break;
+        case 0xf5: // PUSH AF
+            push(cpu, read_af(cpu));
+            break;
+        case 0xfa: // LD A,(u16)
+            cpu->a = read8(cpu, read16(cpu, cpu->pc));
+            cpu->pc += 2;
+            break;
         case 0xfb: // EI
             break;
         default:

src/dmg.c

@@ -18,9 +18,10 @@ void dmg_new(struct dmg *dmg, struct cpu *cpu, struct rom *rom, struct lcd *lcd)
 u8 dmg_read(void *_dmg, u16 address)
 {
     struct dmg *dmg = (struct dmg *) _dmg;
-    if (address < 0x100) {
+//    if (address < 0x100) {
-        return dmg_boot_rom[address];
+//        return dmg_boot_rom[address];
-    } else if (address < 0x4000) {
+//    } else if (address < 0x4000) {
+    if (address < 0x4000) {
         return dmg->rom->data[address];
     } else if (address < 0x8000) {
         // TODO switchable rom bank
@@ -68,6 +69,7 @@ void dmg_write(void *_dmg, u16 address, u8 data)
         // not sure about any of this yet
     }
 }
+void exit(int);
 
 void dmg_step(void *_dmg)
 {
@@ -78,7 +80,8 @@ void dmg_step(void *_dmg)
     cpu_step(dmg->cpu);
 
     // each line takes 456 cycles
-    if (dmg->cpu->cycle_count % 456 == 0) {
+    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);
         if (next_scanline == 144) {
             // vblank has started, draw all the stuff from ram into the lcd
@@ -89,11 +92,14 @@ void dmg_step(void *_dmg)
             int use_unsigned = lcdc & LCDC_BG_TILE_DATA;
             int tilebase = use_unsigned ? 0x8000 : 0x9000;
 
-            printf("base is %04x\n", bg_base);
+            printf("tile map: %04x, tile data: %04x\n", bg_base, tilebase);
 
-            int k, off = 0;
+            int k = 0, off = 0;
-            for (k = 0; k < 1024; k++) {
+            int tile_y = 0, tile_x = 0;
-                int tile = dmg_read(dmg, bg_base + k);
+            for (tile_y = 0; tile_y < 32; tile_y++) {
+                for (tile_x = 0; tile_x < 32; tile_x++) {
+                    off = 256 * 8 * tile_y + 8 * tile_x;
+                    int tile = dmg_read(dmg, bg_base + (tile_y * 32 + tile_x));
                     int eff_addr;
                     if (use_unsigned) {
                         eff_addr = tilebase + 16 * tile;
@@ -104,12 +110,14 @@ void dmg_step(void *_dmg)
                     for (b = 0; b < 16; b += 2) {
                         int data1 = dmg_read(dmg, eff_addr + b);
                         int data2 = dmg_read(dmg, eff_addr + b + 1);
-                    for (i = 0; i < 8; i++) {
+                        for (i = 7; i >= 0; i--) {
                             // monochrome for now
-                        dmg->lcd->buf[off] |= (data1 & (1 << i)) ? 1 : 0;
+                            dmg->lcd->buf[off] = (data1 & (1 << i)) ? 1 : 0;
-                        dmg->lcd->buf[off] |= (data2 & (1 << i)) ? 1 : 0;
+                            //dmg->lcd->buf[off] |= (data2 & (1 << i)) ? 1 : 0;
                             off++;
                         }
+                        off += 248;
+                    }
                 }
             }
 

src/dmg.h

@@ -12,6 +12,7 @@ struct dmg {
     u8 main_ram[0x2000];
     u8 video_ram[0x2000];
     u8 zero_page[0x80];
+    u32 last_lcd_update;
 };
 
 void dmg_new(struct dmg *dmg, struct cpu *cpu, struct rom *rom, struct lcd *lcd);