280 lines
9.3 KiB
C
280 lines
9.3 KiB
C
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#define WIN32_MEAN_AND_LEAN
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#define NOMINMAX
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#include <Windows.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdarg.h>
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#include <stdbool.h>
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typedef struct S86_Buffer S86_Buffer;
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struct S86_Buffer {
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char *data;
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size_t size;
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};
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typedef struct S86_Str8 S86_Str8;
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struct S86_Str8 {
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char *data;
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size_t size;
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};
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typedef struct S86_Globals S86_Globals;
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struct S86_Globals {
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HANDLE stdout_handle;
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};
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S86_Globals s86_globals;
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#define S86_ASSERT(expr) if (!(expr)) { __debugbreak(); }
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#define S86_ARRAY_UCOUNT(array) sizeof((array))/sizeof((array)[0])
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#define S86_STR8(string) (S86_Str8){.data = (string), .size = S86_ARRAY_UCOUNT(string) - 1 }
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#define S86_STR8_FMT(string) (int)((string).size), (string).data
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#define S86_CAST(Type) (Type)
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S86_Buffer S86_ReadFile(char const *file_path)
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{
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S86_Buffer result = {0};
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// NOTE: Determine file size
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// =========================================================================
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WIN32_FILE_ATTRIBUTE_DATA file_attrib_data = {0};
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if (GetFileAttributesEx(file_path, GetFileExInfoStandard, &file_attrib_data) == 0)
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return result;
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// NOTE: Open file
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// =========================================================================
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HANDLE file_handle = CreateFile(
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/*LPCSTR lpFileName*/ file_path,
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/*DWORD dwDesiredAccess*/ GENERIC_READ,
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/*DWORD dwShareMode*/ 0,
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/*LPSECURITY_ATTRIBUTES lpSecurityAttributes*/ NULL,
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/*DWORD dwCreationDisposition*/ OPEN_EXISTING,
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/*DWORD dwFlagsAndAttributes*/ 0,
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/*HANDLE hTemplateFile*/ NULL
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);
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if (file_handle == INVALID_HANDLE_VALUE)
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return result;
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// NOTE: Allocate buffer
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// =========================================================================
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uint64_t file_size = (uint64_t)file_attrib_data.nFileSizeHigh << 32 | (uint64_t)file_attrib_data.nFileSizeLow << 0;
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S86_ASSERT(file_size < (DWORD)-1);
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char *buffer = VirtualAlloc(
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/*LPVOID lpAddress*/ NULL,
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/*SIZE_T dwSize*/ file_size,
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/*DWORD flAllocationType*/ MEM_COMMIT | MEM_RESERVE,
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/*DWORD flProtect*/ PAGE_READWRITE
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);
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if (!buffer)
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goto end;
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// NOTE: Read file to buffer
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// =========================================================================
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DWORD bytes_read = 0;
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BOOL read_file_result = ReadFile(
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/*HANDLE hFile*/ file_handle,
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/*LPVOID lpBuffer*/ buffer,
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/*DWORD nNumberOfBytesToRead*/ S86_CAST(DWORD)file_size,
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/*LPDWORD lpNumberOfBytesRead*/ &bytes_read,
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/*LPOVERLAPPED lpOverlapped*/ NULL
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);
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// NOTE: Handle read result
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// =========================================================================
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if (read_file_result == 0) {
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VirtualFree(buffer, 0, MEM_RELEASE);
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} else {
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result.data = buffer;
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result.size = file_size;
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}
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end:
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CloseHandle(file_handle);
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return result;
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};
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bool S86_BufferIsValid(S86_Buffer buffer)
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{
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bool result = buffer.data && buffer.size;
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return result;
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}
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void S86_PrintLn(S86_Str8 string)
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{
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if (s86_globals.stdout_handle == NULL)
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s86_globals.stdout_handle = GetStdHandle(STD_OUTPUT_HANDLE);
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S86_ASSERT(string.size < S86_CAST(DWORD)-1);
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DWORD chars_written = 0;
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WriteConsoleA(s86_globals.stdout_handle, string.data, (DWORD)string.size, &chars_written, NULL);
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WriteConsoleA(s86_globals.stdout_handle, "\n", 1, &chars_written, NULL);
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}
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void S86_PrintLnFmt(char const *fmt, ...)
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{
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va_list args, args_copy;
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va_start(args, fmt);
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va_copy(args_copy, args);
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int string_size = vsnprintf(NULL, 0, fmt, args_copy);
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va_end(args_copy);
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char buffer[8192];
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S86_ASSERT(string_size >= 0 && string_size < S86_ARRAY_UCOUNT(buffer));
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if (string_size) {
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vsnprintf(buffer, sizeof(buffer), fmt, args);
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S86_Str8 string = {.data = buffer, .size = string_size};
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S86_PrintLn(string);
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}
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va_end(args);
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}
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typedef enum S86_ModEncoding S86_ModEncoding;
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enum S86_ModEncoding {
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S86_ModEncoding_MemModeNoDisplace = 0b00,
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S86_ModEncoding_MemMode8 = 0b01,
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S86_ModEncoding_MemMode16 = 0b10,
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S86_ModEncoding_RegisterMode = 0b11,
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};
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S86_Str8 REGISTER_FIELD_ENCODING[2][8] = {
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[0b0] =
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{
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S86_STR8("AL"),
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S86_STR8("CL"),
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S86_STR8("DL"),
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S86_STR8("BL"),
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S86_STR8("AH"),
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S86_STR8("CH"),
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S86_STR8("DH"),
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S86_STR8("BH"),
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},
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[0b1] =
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{
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S86_STR8("AX"),
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S86_STR8("CX"),
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S86_STR8("DX"),
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S86_STR8("BX"),
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S86_STR8("SP"),
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S86_STR8("BP"),
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S86_STR8("SI"),
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S86_STR8("DI"),
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},
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};
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typedef enum S86_InstructionType S86_InstructionType;
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enum S86_InstructionType {
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S86_InstructionType_MOVRegOrMemToOrFromReg,
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S86_InstructionType_MOVImmediateToRegOrMem,
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S86_InstructionType_MOVImmediateToReg,
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S86_InstructionType_MOVMemToAccum,
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S86_InstructionType_MOVAccumToMem,
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S86_InstructionType_MOVRegOrMemToSegReg,
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S86_InstructionType_MOVSegRegToRegOrMem,
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S86_InstructionType_Count,
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};
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typedef struct S86_Instruction S86_Instruction;
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struct S86_Instruction {
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uint16_t op_mask;
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uint16_t op_bits;
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} S86_INSTRUCTIONS[S86_InstructionType_Count] = {
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[S86_InstructionType_MOVRegOrMemToOrFromReg] = {.op_mask = 0b1111'1100'0000'0000, .op_bits = 0b1000'1000'0000'0000},
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[S86_InstructionType_MOVImmediateToRegOrMem] = {.op_mask = 0b1111'1110'0011'1000, .op_bits = 0b1100'0110'0000'0000},
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[S86_InstructionType_MOVImmediateToReg] = {.op_mask = 0b1111'0000'0000'0000, .op_bits = 0b1011'0000'0000'0000},
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[S86_InstructionType_MOVMemToAccum] = {.op_mask = 0b1111'1110'0000'0000, .op_bits = 0b1010'0000'0000'0000},
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[S86_InstructionType_MOVAccumToMem] = {.op_mask = 0b1111'1110'0000'0000, .op_bits = 0b1010'0010'0000'0000},
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[S86_InstructionType_MOVRegOrMemToSegReg] = {.op_mask = 0b1111'1111'0010'0000, .op_bits = 0b1000'1110'0000'0000},
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[S86_InstructionType_MOVSegRegToRegOrMem] = {.op_mask = 0b1111'1111'0010'0000, .op_bits = 0b1000'1100'0000'0000},
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};
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typedef enum S86_OpDataSize S86_OpDataSize;
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enum S86_OpDataSize { S86_OpDataSize_Byte, S86_OpDataSize_Word };
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int main(int argc, char **argv)
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{
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if (argc != 2) {
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S86_PrintLn(S86_STR8("usage: sim8086.exe <binary asm file>"));
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return -1;
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}
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char const *file_path = argv[1];
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S86_Buffer buffer = S86_ReadFile(file_path);
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if (!S86_BufferIsValid(buffer)) {
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S86_PrintLnFmt("File read failed [path=\"%s\"]", argv[1], buffer.size);
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return -1;
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}
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S86_ASSERT(buffer.size % 2 == 0); // We expect 2 byte instructions
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for (size_t buffer_index = 0; buffer_index < (buffer.size / 2); buffer_index++) {
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char byte0 = buffer.data[buffer_index + 0];
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char byte1 = buffer.data[buffer_index + 1];
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uint16_t byte01 = (uint16_t)byte0 << 8 | (uint16_t)byte1 << 0;
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for (size_t instruction_index = 0;
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instruction_index < S86_ARRAY_UCOUNT(S86_INSTRUCTIONS);
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instruction_index++)
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{
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S86_Instruction instruction = S86_INSTRUCTIONS[instruction_index];
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if ((byte01 & instruction.op_mask) != instruction.op_bits)
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continue;
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S86_InstructionType type = S86_CAST(S86_InstructionType)instruction_index;
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switch (type) {
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case S86_InstructionType_MOVRegOrMemToOrFromReg: {
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uint8_t d = (byte0 & 0b0000'0010) >> 1;
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uint8_t w = (byte0 & 0b0000'0001) >> 0;
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uint8_t mod = (byte1 & 0b1100'0000) >> 6;
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uint8_t reg = (byte1 & 0b0011'1000) >> 3;
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uint8_t rm = (byte1 & 0b0000'0111) >> 0;
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uint8_t instr_dest = d ? reg : rm;
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uint8_t instr_src = d ? rm : reg;
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S86_OpDataSize data_size = w ? S86_OpDataSize_Word : S86_OpDataSize_Byte;
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S86_ASSERT(mod == 0b11); // register-to-register
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S86_Str8 src_register = REGISTER_FIELD_ENCODING[w][instr_src];
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S86_Str8 dest_register = REGISTER_FIELD_ENCODING[w][instr_dest];
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S86_PrintLnFmt("MOV %.*s %.*s", S86_STR8_FMT(src_register), S86_STR8_FMT(dest_register));
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#if 0
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if (mod == 0b01) {
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// 8 bit displacement
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} else if (mode == 0b10) {
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// 16 bit displacement
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}
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#endif
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} break;
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case S86_InstructionType_MOVImmediateToRegOrMem: {
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} break;
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case S86_InstructionType_MOVImmediateToReg: {
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} break;
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case S86_InstructionType_MOVMemToAccum: {
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} break;
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case S86_InstructionType_MOVAccumToMem: {
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} break;
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case S86_InstructionType_MOVRegOrMemToSegReg: {
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} break;
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case S86_InstructionType_MOVSegRegToRegOrMem: {
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} break;
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default: {
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S86_ASSERT(!"Unknown instruction");
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} break;
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}
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}
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}
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}
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