Added extra memory regions and default value of memory

subratkatiyar · May 1, 2024 · a15ad51 · a15ad51
1 parent 8b6e976
commit a15ad51
Show file tree

Hide file tree

Showing 7 changed files with 257 additions and 84 deletions.
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -9,6 +9,7 @@ set(SOURCES
     src/main.c
     src/memory.c
     src/cpu.c
+    src/INS_load.c
     # Add other source files here as needed
 )
 

diff --git a/README.md b/README.md
@@ -43,6 +43,23 @@ Trying to emulate gameboy for understanding how a CPU works in general
 | Ex                 |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
 | Fx                 |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
 
+# Memory Regions Observartions.
+0x0000 - 0x3FFF = Fixed from cartridge </br>
+0x4000 - 0x7FFF = Switchable from cartridge </br>
+0x8000 - 0x9FFF = VIDEO RAM ?? </br>
+0xA000 - 0xBFFF = 0xFF </br> 
+0xC000 - 0xCFFF = Random </br>
+0xD000 - 0xDFFF = Random </br>
+0xE000 - 0xFDFF = Echo Ram 0xC000 to 0xDDFF </br>
+0xFE00 - 0xFE9F = Random </br>
+0xFEA0 - 0xFEFF = 0x00 </br>
+
+0xFF00 - 0xFF2F = Constant. </br>
+0xFF30 - 0xFF3F = Random. </br>
+0xFF40 - 0xFF7F = Constant. </br>
+
+0xFF80 - 0xFFFE = Random. </br>
+0xFFFF = 0x00 </br>
 
 ## Important Links
 - OPCodes: https://gbdev.io/gb-opcodes/optables/
diff --git a/include/INS_load.h b/include/INS_load.h
@@ -0,0 +1,10 @@
+#include "memory.h"
+
+void execute_load_1(GameboyMemory *memory, GameboyRegisters *registers);
+void execute_load_2(GameboyMemory *memory, GameboyRegisters *registers);
+void execute_load_3(GameboyMemory *memory, GameboyRegisters *registers);
+void execute_load_4(GameboyMemory *memory, GameboyRegisters *registers);
+void execute_load_5(GameboyMemory *memory, GameboyRegisters *registers);
+void execute_load_6(GameboyMemory *memory, GameboyRegisters *registers);
+void execute_load_7(GameboyMemory *memory, GameboyRegisters *registers);
+void execute_load_8(GameboyMemory *memory, GameboyRegisters *registers);
diff --git a/include/memory.h b/include/memory.h
@@ -10,7 +10,9 @@
 #define VRAM_SIZE       0x2000  // Video RAM size (8KB)
 #define ERAM_SIZE       0x2000  // External RAM size (8KB)
 #define WRAM_SIZE       0x2000  // Working RAM size (8KB)
+#define ECHO_RAM        0x1E00  // Echo Ram [New]
 #define OAM_SIZE        0xA0    // Object Attribute Memory size (160 bytes)
+#define NOT_USABLE      0x60    // Not Usable [New]
 #define IO_SIZE         0x80    // I/O Registers size (128 bytes)
 #define HRAM_SIZE       0x7F    // High RAM size (127 bytes)
 
@@ -20,7 +22,9 @@ typedef struct {
     uint8_t vram[VRAM_SIZE];    // Video RAM
     uint8_t eram[ERAM_SIZE];    // External RAM (cartridge RAM)
     uint8_t wram[WRAM_SIZE];    // Working RAM
+    uint8_t echoram[ECHO_RAM];  // Echo Ram [New]
     uint8_t oam[OAM_SIZE];      // Object Attribute Memory
+    uint8_t notuse[NOT_USABLE]; // Not Usable [New]
     uint8_t io[IO_SIZE];        // I/O Registers
     uint8_t hram[HRAM_SIZE];    // High RAM
     uint8_t ie;                 // Interrupt Enable Register

diff --git a/src/INS_load.c b/src/INS_load.c
@@ -0,0 +1,69 @@
+#include <stdio.h>
+#include "INS_load.h"
+
+void execute_load_1(GameboyMemory *memory, GameboyRegisters *registers){
+    uint16_t valueLoc = registers->pc + 0x01;
+    uint16_t value = read_memory_16_le(memory, valueLoc);
+    printf("LOAD HL 0x%04X\n", value); 
+    registers->hl = value;
+    registers->pc += 0x03;
+}
+
+void execute_load_2(GameboyMemory *memory, GameboyRegisters *registers){
+    uint16_t valueLoc = registers->pc + 0x01;
+    uint16_t value = read_memory(memory, valueLoc);
+    printf("LOAD C 0x%02X\n", value); 
+    registers->c = value;
+    registers->pc += 0x02;
+}
+
+void execute_load_3(GameboyMemory *memory, GameboyRegisters *registers){
+    uint16_t valueLoc = registers->pc + 0x01;
+    uint16_t value = read_memory(memory, valueLoc);
+    printf("LOAD B 0x%02X\n", value); 
+    registers->b = value;
+    registers->pc += 0x02;
+}
+
+void execute_load_4(GameboyMemory *memory, GameboyRegisters *registers){
+    uint8_t value = registers->a;
+    printf("LOAD *HL A\n"); 
+    write_memory(memory, registers->hl, value);
+    registers->hl -= 0x01;
+    registers->pc += 0x01;
+}
+
+void execute_load_5(GameboyMemory *memory, GameboyRegisters *registers){
+    printf("LOAD L C\n"); 
+    registers->l = registers->c;
+    registers->pc += 0x01;
+}
+
+void execute_load_6(GameboyMemory *memory, GameboyRegisters *registers){
+    uint16_t valueLoc = registers->pc + 0x01;
+    uint8_t value = read_memory(memory, valueLoc);
+    printf("LOAD A 0x%02X\n", value);
+    registers->a = value; 
+    registers->pc += 0x02;
+}
+
+void execute_load_7(GameboyMemory *memory, GameboyRegisters *registers){
+    uint16_t valueLoc = registers->pc + 0x01;
+    uint8_t value = read_memory(memory, valueLoc);
+    printf("LOAD FF00+ 0x%02X, A\n", value); 
+
+    uint16_t address = 0xFF00 + value;
+    write_memory(memory, address, registers->a);
+
+    registers->pc += 0x02;
+}
+
+void execute_load_8(GameboyMemory *memory, GameboyRegisters *registers){
+    uint16_t valueLoc = registers->pc + 0x01;
+    uint8_t value = read_memory(memory, valueLoc);
+    uint16_t address = 0xFF00 + value;
+    value = read_memory(memory, address);
+    printf("LOAD A, FF00+ 0x%02X, A\n", value); 
+    registers->a = value;
+    registers->pc += 0x02;
+}
diff --git a/src/cpu.c b/src/cpu.c
@@ -71,57 +71,7 @@ void execute_xor(GameboyRegisters *registers){
     registers->pc += 0x01;
 }
 
-void execute_load_1(GameboyMemory *memory, GameboyRegisters *registers){
-    uint16_t valueLoc = registers->pc + 0x01;
-    uint16_t value = read_memory_16_le(memory, valueLoc);
-    printf("LOAD HL 0x%04X\n", value); 
-    registers->hl = value;
-    registers->pc += 0x03;
-}
-
-void execute_load_2(GameboyMemory *memory, GameboyRegisters *registers){
-    uint16_t valueLoc = registers->pc + 0x01;
-    uint16_t value = read_memory(memory, valueLoc);
-    printf("LOAD C 0x%02X\n", value); 
-    registers->c = value;
-    registers->pc += 0x02;
-}
-
-void execute_load_3(GameboyMemory *memory, GameboyRegisters *registers){
-    uint16_t valueLoc = registers->pc + 0x01;
-    uint16_t value = read_memory(memory, valueLoc);
-    printf("LOAD B 0x%02X\n", value); 
-    registers->b = value;
-    registers->pc += 0x02;
-}
-
-void execute_load_4(GameboyMemory *memory, GameboyRegisters *registers){
-    uint8_t value = registers->a;
-    printf("LOAD *HL A\n"); 
-    write_memory(memory, registers->hl, value);
-    registers->hl -= 0x01;
-    registers->pc += 0x01;
-}
-
-void execute_load_5(GameboyMemory *memory, GameboyRegisters *registers){
-    printf("LOAD L C\n"); 
-    registers->l = registers->c;
-    registers->pc += 0x01;
-}
 
-void execute_load_6(GameboyMemory *memory, GameboyRegisters *registers){
-    uint16_t valueLoc = registers->pc + 0x01;
-    uint8_t value = read_memory(memory, valueLoc);
-    printf("LOAD A 0x%02X\n", value);
-    registers->a = value; 
-    registers->pc += 0x02;
-}
-
-void execute_load_7(GameboyMemory *memory, GameboyRegisters *registers){
-    printf("LOAD L C\n"); 
-    registers->l = registers->c;
-    registers->pc += 0x01;
-}
 
 void execute_decrease_1(GameboyMemory *memory, GameboyRegisters *registers){
     printf("DEC B\n");
@@ -198,6 +148,19 @@ void execute_disable_interrupts(GameboyRegisters *registers){
     registers->pc += 0x01;
 }
 
+void execute_compare_1(GameboyMemory *memory, GameboyRegisters *registers){
+    // registers->pc += 0x01;
+    // int8_t n = (int8_t)read_memory(memory, registers->pc);
+    // registers->pc += 0x01;
+
+    // printf("CP A 0x%02X\n", n); 
+    // if(registers->a == n)
+    //     registers->f = 1;
+    // else
+    //     registers->z = 0;
+
+}
+
 void execute_instruction(GameboyMemory *memory, GameboyRegisters *registers, uint8_t opcode){
     switch(opcode){
         case 0x00:
@@ -239,7 +202,12 @@ void execute_instruction(GameboyMemory *memory, GameboyRegisters *registers, uin
         case 0xE0:
             execute_load_7(memory, registers);
             break;
-
+        case 0xF0:
+            execute_load_8(memory, registers);
+            break;
+        case 0xFE:
+            execute_compare_1(memory, registers);
+            break;
         // case 0x69:
         //     execute_load_5(memory, registers);
         //     break;