Improved debug display.

Bug fixes: POPD and POPP now pull bytes from the stack in proper order.

Source/assembly.c

@@ -0,0 +1,80 @@
+// assembly.c
+// These are functions useful for translating assembly mnemonics to hex and vice-versa for the SplitBit CPU.
+// Written by Anachronaut
+// 10/18/2024
+
+#include "assembly.h"
+
+typedef struct {
+    uint8_t opcode;
+    const char* mnemonic;
+} Instruction;
+
+Instruction instruction_set[] = {
+    // Arithmetic and Logic Operations:
+    {0x00, "ADD"},
+    {0x01, "SUB"},
+    {0x02, "AND"},
+    {0x03, "OR"},
+    {0x04, "NOR"},
+    {0x05, "NAND"},
+    {0x06, "XOR"},
+    {0x07, "NOTA"},
+    {0x08, "NOTB"},
+    // Branch Operations:
+    {0x10, "BRI"},
+    {0x11, "BRQ"},
+    {0x12, "BRA"},
+    {0x13, "BRB"},
+    // Register Operations:
+    {0x20, "RSTA"},
+    {0x21, "RSTB"},
+    {0x22, "INCA"},
+    {0x23, "INCB"},
+    {0x24, "DECA"},
+    {0x25, "DECB"},
+    {0x26, "LDA"},
+    {0x27, "LDB"},
+    {0x28, "INIA"},
+    {0x29, "INIB"},
+    // Stack Operations:
+    {0x30, "PSHQ"},
+    {0x31, "PSHA"},
+    {0x32, "PSHB"},
+    {0x33, "PSHP"},
+    {0x34, "PSHD"},
+    {0x35, "POPA"},
+    {0x36, "POPB"},
+    {0x37, "POPP"},
+    {0x38, "POPD"},
+    // Data Operations:
+    {0x40, "INCD"},
+    {0x41, "DECD"},
+    {0x42, "LDA"},
+    {0x43, "LDB"},
+    {0x44, "STQ"},
+    {0x45, "STA"},
+    {0x46, "STB"},
+    {0x47, "SETD"},
+    // Output Operations:
+    {0xD0, "OUTQ"},
+    {0xD1, "OUTA"},
+    {0xD2, "OUTB"},
+    // Input Operations:
+    {0xE0, "INA"},
+    {0xE1, "INB"},
+    {0xE2, "IND"},
+    // Special Operations:
+    {0xF0, "NOP"},
+    {0xFF, "HALT"}
+};
+
+const char* getMnemonic(uint8_t opcode) {
+    int num_instructions = sizeof(instruction_set) / sizeof(Instruction);
+    for (int i = 0; i < num_instructions; i++) {
+        if (instruction_set[i].opcode == opcode) {
+            return instruction_set[i].mnemonic;
+        }
+    }
+    return "---";
+}

Source/assembly.h

@@ -0,0 +1,13 @@
+// assembly.c
+// These are functions useful for translating assembly mnemonics to hex and vice-versa for the SplitBit CPU.
+// Written by Anachronaut
+// 10/18/2024
+
+#include <stdint.h>
+
+#ifndef ASSEMBLY_H
+#define ASSEMBLY_H
+
+const char* getMnemonic(uint8_t opcode);
+
+#endif // CPU_H

Source/cpu.c

@@ -206,18 +206,18 @@ uint8_t executeOperation(uint8_t Instruction, CPURegisters *cpu) {
         break;
         case 0x37:
             // POPP - Pop Data to the Program Counter
+            cpu->StackPointer++;
             cpu->ProgramCounter = (uint16_t)cpu->Data[cpu->StackPointer] << 8;
             cpu->StackPointer++;
             cpu->ProgramCounter = cpu->ProgramCounter | (uint16_t)cpu->Data[cpu->StackPointer];
             cpu->ProgramCounter += 3; // Because it needs to skip over the subsequent branch instruction on return.
-            cpu->StackPointer++;
         break;
         case 0x38:
             // POPD - Pop Data to the Data Pointer
+            cpu->StackPointer++;
             cpu->DataPointer = (uint16_t)cpu->Data[cpu->StackPointer] << 8;
             cpu->StackPointer++;
             cpu->DataPointer |= (uint16_t)cpu->Data[cpu->StackPointer];
-            cpu->StackPointer++;
         break;
         //
         // 4x - Data Operations:

Source/utility.c

@@ -7,6 +7,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <getopt.h>
+#include "assembly.h"
 
 void printHelp(const char *programName) {
     printf("Usage: %s [OPTIONS] <binaryfile>\n", programName);
@@ -48,8 +49,8 @@ uint8_t parseOptions(int argc, char *argv[]) {
 void printRegisters(CPURegisters *cpu, uint8_t *Program, uint8_t *Data) {
     printf("***** CPU Registers *****\n");
     printf("A: 0x%02X\tB: 0x%02X\tQ: 0x%02X\tStatus: 0b%08b\n", cpu->A, cpu->B, cpu->Q, cpu->Status);
-    printf("Program Counter: 0x%04X     Current Instruction: 0x%02X\n", cpu->ProgramCounter, Program[cpu->ProgramCounter]);
+    printf("Program Counter: 0x%04X     Current Instruction: 0x%02X (%s)\n", cpu->ProgramCounter, Program[cpu->ProgramCounter],getMnemonic(Program[cpu->ProgramCounter]));
     printf("   Data Pointer: 0x%04X      Current Data Value: 0x%02X\n", cpu->DataPointer, Data[cpu->DataPointer]);
-    printf("  Stack Pointer: 0x%04X           Current Value: 0x%02X\n", cpu->StackPointer, Data[cpu->StackPointer]);
+    printf("  Stack Pointer: 0x%04X           Current Value: (0x%02X) (0x%02X)\n", Data[cpu->StackPointer], Data[cpu->StackPointer+1], Data[cpu->StackPointer+2]);
 }