123 lines
2.8 KiB
C
123 lines
2.8 KiB
C
// assembly.c
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// These are functions useful for translating assembly mnemonics to hex and vice-versa for the SplitBit CPU.
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// Written by Anachronaut
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// 10/18/2024
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#include "assembly.h"
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#include <string.h>
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typedef struct {
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uint8_t opcode;
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const char* mnemonic;
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} Instruction;
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Instruction instruction_set[] = {
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// Arithmetic and Logic Operations:
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{0x00, "ADD"},
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{0x01, "SUB"},
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{0x02, "AND"},
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{0x03, "OR"},
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{0x04, "XOR"},
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{0x05, "NOTA"},
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{0x06, "NOTB"},
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{0x07, "SHL"},
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{0x08, "SHR"},
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// Branch Operations:
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{0x10, "BRI"},
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{0x11, "BRQ"},
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{0x12, "BRA"},
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{0x13, "BRB"},
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{0x14, "BRC"},
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{0x17, "CALL"},
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{0x1F, "RET"},
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// Register Operations:
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{0x20, "RSTA"},
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{0x21, "RSTB"},
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{0x22, "INCA"},
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{0x23, "INCB"},
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{0x24, "DECA"},
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{0x25, "DECB"},
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{0x26, "INIA"},
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{0x27, "INIB"},
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{0x28, "CCF"},
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// Stack Operations:
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{0x30, "PSHQ"},
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{0x31, "PSHA"},
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{0x32, "PSHB"},
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{0x33, "PSHD"},
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{0x34, "POPA"},
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{0x35, "POPB"},
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{0x36, "POPD"},
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// Data Operations:
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{0x40, "INCD"},
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{0x41, "DECD"},
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{0x42, "LDA"},
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{0x43, "LDB"},
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{0x44, "STQ"},
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{0x45, "STA"},
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{0x46, "STB"},
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{0x47, "SETD"},
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{0x48, "DPUP"},
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{0x49, "DPDN"},
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{0x4A, "LDD"},
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{0x4B, "STD"},
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// Output Operations:
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{0xD0, "OUTQ"},
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{0xD1, "OUTA"},
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{0xD2, "OUTB"},
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// Input Operations:
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{0xE0, "INA"},
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{0xE1, "INB"},
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// Special Operations:
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{0xF0, "NOP"},
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{0xFF, "HALT"}
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};
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int num_instructions = sizeof(instruction_set) / sizeof(Instruction);
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const char* getMnemonic(uint8_t opcode) {
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for (int i = 0; i < num_instructions; i++) {
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if (instruction_set[i].opcode == opcode) {
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return instruction_set[i].mnemonic;
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}
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}
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return "---";
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}
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int dataPointerOperands(uint8_t opcode) {
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// How many Data Pointer selector bytes follow this opcode. Most instructions
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// have none. The ones that work through a pointer have one naming which pointer.
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// LDD and STD move a pointer through a pointer, so they name two.
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switch (opcode) {
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case 0x4A: // LDD
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case 0x4B: // STD
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return 2;
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case 0x33: // PSHD
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case 0x36: // POPD
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case 0x40: // INCD
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case 0x41: // DECD
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case 0x42: // LDA
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case 0x43: // LDB
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case 0x44: // STQ
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case 0x45: // STA
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case 0x46: // STB
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case 0x47: // SETD
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case 0x48: // DPUP
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case 0x49: // DPDN
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return 1;
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default:
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return 0;
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}
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}
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uint8_t getOpcode(char* mnemonic) {
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for (int i = 0; i < num_instructions; i++) {
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if (strcmp(instruction_set[i].mnemonic, mnemonic) == 0) {
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return instruction_set[i].opcode;
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}
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}
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return 0xFE; // FE is an unused instruction, we'll use it to indicate an error.
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}
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