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vm.c
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vm.c
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#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#include <SDL2/SDL.h>
#include <limits.h>
#include <math.h>
#include <time.h>
// global constants
#define ROM_SLOTS 65535
#define RAM_SLOTS 65535
#define STACK_FRAME_SIZE 128
#define STACK_MAX_SIZE 32
#define VRAM_FIRST_INDEX 4101
#define MAX_RAMVALUE UINT_MAX
#define DEBUG 0
uint32_t rom[ROM_SLOTS]; // rom
uint32_t ram[RAM_SLOTS]; // ram
int16_t sp; // stack pointer
int16_t stack[STACK_MAX_SIZE]; // stack
int init_pc(void)
{
FILE* file = fopen("start_pc.txt", "r");
int pc = 0;
fscanf(file, "%d\n", &pc);
fclose(file);
return pc;
}
uint16_t letter_code_to_ram_index(uint16_t letter_code)
{
switch(letter_code)
{
case 1: {
return 4096; // U
}
case 2: {
return 4097; // V
}
case 3: {
return 4098; // Y
}
case 4: {
return 4099; // Z
}
}
return 0; // <- should never happen
}
void arraySliceAssignment(uint32_t array0[ ],
uint32_t array1[ ],
uint32_t i,
uint32_t j,
uint32_t width)
{
// i: array0 start index
// j: array1 start index
//
// equivalent to `array0[i:i+width] = array1[j:j+width]` in Python
for(uint32_t x = 0; x < width; x++)
{
if((array1[j+x] & 0xFF) == 255) // check if alpha is 0XFF
{
array0[i+x] = array1[j+x];
}
}
}
void convert_endianess(void)
{
for(int32_t i = 0; i < ROM_SLOTS; i++)
{
const uint32_t temp = rom[i];
rom[i] =
(((temp >> 24) & 0xFF) << 0x00) | (((temp >> 16) & 0xFF) << 0x08) |
(((temp >> 8) & 0xFF) << 0x10) | (((temp >> 0) & 0xFF) << 0x18);
}
}
int main(int argc, char* argv[])
{
srand(time(NULL));
if(argc != 2)
{
puts("./a.out file_r.bin");
exit(1);
}
const int xres = 160;
const int yres = 144;
const int resize = 3;
SDL_Window* window = SDL_CreateWindow("vlahb vm", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, xres, yres, SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE );
SDL_SetWindowSize(window, xres * resize, yres * resize);
SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
SDL_Texture* texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_STREAMING, xres, yres);
FILE* fp = fopen(argv[1], "rb");
fread(rom, sizeof(uint32_t), ROM_SLOTS, fp);
convert_endianess();
bool done = false;
int pc = init_pc();
while(!done)
{
const uint32_t word0 = rom[pc + 0];
const uint32_t word1 = rom[pc + 1];
const uint16_t word0_first_half = (word0 >> 16) & 0xFFFF;
const uint16_t word0_second_half = (word0 >> 0) & 0xFFFF;
const uint16_t word1_first_half = (word1 >> 16) & 0xFFFF;
const uint16_t word1_second_half = (word1 >> 0) & 0xFFFF;
#if DEBUG == 1
printf(" %08X\n", word0);
printf(" %08X\n", word1);
printf("\n");
printf(" STACK -> [%u,%u,%u,..]\n", stack[0],stack[1],stack[2]);
printf(" PROGRAM COUNTER -> %i\n", pc);
printf(" STACK POINTER -> %i\n", sp);
printf("\n");
for(int rrr = 0; rrr<5; rrr++)
{
printf(" RAM[000%u]: %u\n", rrr, ram[rrr]);
}
printf("\n");
printf(" RAM[4096]: %u // pointer U\n", ram[4096]);
printf(" RAM[4097]: %u // pointer V\n", ram[4097]);
printf(" RAM[4098]: %u // pointer Y\n", ram[4098]);
printf(" RAM[4099]: %u // pointer Z\n", ram[4099]);
printf(" RAM[4100]: %u // return\n", ram[4100]);
printf("\n -----------\n\n");
#endif
pc += 2;
switch(word0_second_half)
{
case 0x0001: // GOTO LABEL, GOTO k //
{
pc = word1;
break;
}
case 0x0002: // GOTO R[i] //
{
pc = ram[word1];
break;
}
case 0x0003: // DIRECT LOAD //
{
ram[word0_first_half] = word1;
break;
}
case 0x0004: // DIRECT ADD //
{
ram[word0_first_half] += word1;
break;
}
case 0x0005: // DIRECT SUBTRACT //
{
ram[word0_first_half] -= word1;
break;
}
case 0x0006: // DIRECT MULTIPLY //
{
ram[word0_first_half] *= word1;
break;
}
case 0x0007: // DIRECT DIVIDE //
{
ram[word0_first_half] /= word1;
break;
}
case 0x0008: // REGISTER TO REGISTER LOAD //
{
ram[word0_first_half] = ram[word1];
break;
}
case 0x0009: // REGISTER TO REGISTER ADD //
{
ram[word0_first_half] += ram[word1];
break;
}
case 0x000a: // REGISTER TO REGISTER SUBTRACT //
{
ram[word0_first_half] -= ram[word1];
break;
}
case 0x000b: // REGISTER TO REGISTER MULTIPLY //
{
ram[word0_first_half] *= ram[word1];
break;
}
case 0x000c: // REGISTER TO REGISTER DIVIDE //
{
ram[word0_first_half] /= ram[word1];
break;
}
case 0x000d: // COMPARE REGISTER TO DIRECT //
{
if(ram[word0_first_half] == word1) pc += 2;
break;
}
case 0x000e: // COMPARE REGISTER TO REGISTER //
{
if(ram[word0_first_half] == ram[word1]) pc += 2;
break;
}
case 0x000f: // COMPARE UV TO DIRECT //
{
const uint16_t i = (word0_first_half >> 12) & 0XF; // i000
const uint16_t ram_index_i = letter_code_to_ram_index(i);
if(ram[ram[ram_index_i]] == word1) pc += 2;
break;
}
case 0x0010: // CALL LABEL, CALL k//
{
stack[sp] = pc;
int a = STACK_FRAME_SIZE * (0 + sp);
int b = STACK_FRAME_SIZE * (1 + sp);
for(int x = 0; x < b; x++) ram[a + x] = ram[0 + x];
sp += 1; // increment stack pointer
pc = word1;
break;
}
case 0x0011: // CALL R[i] //
{
stack[sp] = pc;
int a = STACK_FRAME_SIZE * (0 + sp);
int b = STACK_FRAME_SIZE * (1 + sp);
for(int x = 0; x < b; x++) ram[a + x] = ram[0 + x];
sp += 1; // increment stack pointer
pc = ram[word1];
break;
}
case 0x0012: // RETURN //
{
int a = STACK_FRAME_SIZE * (0 + sp);
int b = STACK_FRAME_SIZE * (1 + sp);
for(int x = 0; x < b; x++) ram[0 + x] = ram[a + x];
// pop from stack and assign to pc
sp -= 1;
pc = stack[sp];
break;
}
case 0x0013: // STRICT LESS THAN REGISTER TO DIRECT a < b //
{
if(ram[word0_first_half] < word1) pc += 2;
break;
}
case 0x0014: // STRICT LESS THAN REGISTER TO REGISTER a < b //
{
if(ram[word0_first_half] < ram[word1]) pc += 2;
break;
}
case 0x0015: // LESS THAN OR EQUAL REGISTER TO DIRECT a <= b //
{
if(ram[word0_first_half] <= word1) pc += 2;
break;
}
case 0x0016: // LESS THAN OR EQUAL REGISTER TO REGISTER a <= b //
{
if(ram[word0_first_half] <= ram[word1]) pc += 2;
break;
}
case 0x0017: // STRICT GREATER THAN REGISTER TO DIRECT a > b //
{
if(ram[word0_first_half] > word1) pc += 2;
break;
}
case 0x0018: // STRICT GREATER THAN REGISTER TO REGISTER a > b //
{
if(ram[word0_first_half] > ram[word1]) pc += 2;
break;
}
case 0x0019: // GREATER THAN OR EQUAL REGISTER TO DIRECT a >= b //
{
if(ram[word0_first_half] >= word1) pc += 2;
break;
}
case 0x001a: // GREATER THAN OR EQUAL REGISTER TO REGISTER a >= b //
{
if(ram[word0_first_half] >= ram[word1]) pc += 2;
break;
}
case 0x001b: // BLIT //
{
void* raw;
int32_t pitch;
SDL_LockTexture(texture, NULL, &raw, &pitch);
uint32_t* pixels = (uint32_t*) raw;
for(int y = 0; y < yres; y++)
for(int x = 0; x < xres; x++)
pixels[x + y * xres] = ram[VRAM_FIRST_INDEX + x + y * xres];
SDL_UnlockTexture(texture);
SDL_RenderCopy(renderer, texture, NULL, NULL);
SDL_RenderPresent(renderer);
break;
}
case 0x001c: // RAND //
{
int random_bit = rand() % 2;
ram[word1] = random_bit;
break;
}
case 0x001d: // LD ARRAY TO VRAM //
{
// syntax: LD MARIO R[X] R[Y] W H
const uint16_t label_idx = word0_first_half;
const uint16_t x_sprite = (rom[pc - 1] >> 24) & 0xFF;
const uint16_t y_sprite = (rom[pc - 1] >> 16) & 0XFF;
const uint16_t width_sprite = (rom[pc - 1] >> 8) & 0XFF;
const uint16_t height_sprite = (rom[pc - 1]) & 0xFF;
const uint16_t vram_idx = 4101 + ram[x_sprite] + 160*ram[y_sprite];
for(int h = 0; h < height_sprite; h++)
{
arraySliceAssignment(
ram, rom, vram_idx + (h*160),
label_idx + h*width_sprite,
width_sprite
);
}
break;
}
case 0x001e: // LD ARRAY PC TO REGISTER //
{
// syntax: LD R[i] ARRAY
ram[word1_second_half] = word0_first_half;
break;
}
case 0x001f: // LD REGISTERS TO VRAM //
{
// syntax: LD R[U] R[i] R[j] R[k] R[l] //
const uint16_t i = (word0_first_half >> 12) & 0XF; // i000
const uint16_t ram_index_i = letter_code_to_ram_index(i);
const uint16_t x_sprite = (rom[pc - 1] >> 24) & 0xFF;
const uint16_t y_sprite = (rom[pc - 1] >> 16) & 0XFF;
const uint16_t width_sprite = (rom[pc - 1] >> 8) & 0XFF;
const uint16_t height_sprite = (rom[pc - 1]) & 0xFF;
const uint16_t vram_idx = 4101 + ram[x_sprite] + 160*ram[y_sprite];
for(uint16_t h = 0; h < ram[height_sprite]; h++)
{
arraySliceAssignment(
ram, rom, vram_idx + (h*160),
ram[ram_index_i] + h*ram[width_sprite],
ram[width_sprite]
);
}
break;
}
case 0x0020: // LD R[U] R[V] //
{
const uint16_t i = (word0_first_half >> 12) & 0XF; // i000
const uint16_t j = (word0_first_half >> 8) & 0XF; // 0j00
const uint16_t ram_index_i = letter_code_to_ram_index(i);
const uint16_t ram_index_j = letter_code_to_ram_index(j);
ram[ram[ram_index_i]] = ram[ram[ram_index_j]];
break;
}
case 0x0021: // LD R[U:V] R[Y] //
{
const uint16_t i = (word0_first_half >> 12) & 0XF; // i000
const uint16_t j = (word0_first_half >> 8) & 0XF; // 0j00
const uint16_t k = (word0_first_half >> 4) & 0XF; // 00k0
const uint16_t ram_index_i = letter_code_to_ram_index(i);
const uint16_t ram_index_j = letter_code_to_ram_index(j);
const uint16_t ram_index_k = letter_code_to_ram_index(k);
int32_t array_span = ram[ram_index_j] - ram[ram_index_i];
for(int idx = 0; idx < array_span; idx++)
{
ram[ram[ram_index_i] + idx] = ram[ram[ram_index_k]];
}
break;
}
case 0x0022: // LD R[U:V] R[Y:Z] //
{
const uint16_t i = (word0_first_half >> 12) & 0XF; // i000
const uint16_t j = (word0_first_half >> 8) & 0XF; // 0j00
const uint16_t k = (word0_first_half >> 4) & 0XF; // 00k0
// does not use 000l bit
const uint16_t ram_index_i = letter_code_to_ram_index(i);
const uint16_t ram_index_j = letter_code_to_ram_index(j);
const uint16_t ram_index_k = letter_code_to_ram_index(k);
int32_t array_span = ram[ram_index_j] - ram[ram_index_i];
for(int idx = 0; idx < array_span; idx++)
{
ram[ram[ram_index_i] + idx] = ram[ram[ram_index_k] + idx];
}
break;
}
case 0x0023: // LD R[U:V] R[i] //
{
const uint16_t i = (word0_first_half >> 12) & 0XF; // i000
const uint16_t j = (word0_first_half >> 8) & 0XF; // 0j00
const uint16_t ram_index_i = letter_code_to_ram_index(i);
const uint16_t ram_index_j = letter_code_to_ram_index(j);
int32_t array_span = ram[ram_index_j] - ram[ram_index_i];
for(int idx = 0; idx < array_span; idx++)
{
ram[ram[ram_index_i] + idx] = ram[word1];
}
break;
}
case 0x0024: // LD R[U] R[i] //
{
const uint16_t i = (word0_first_half >> 12) & 0XF; // i000
const uint16_t ram_index_i = letter_code_to_ram_index(i);
ram[ram[ram_index_i]] = ram[word1];
break;
}
case 0x0025: // LD R[U] i //
{
const uint16_t i = (word0_first_half >> 12) & 0XF; // i000
const uint16_t ram_index_i = letter_code_to_ram_index(i);
ram[ram[ram_index_i]] = word1;
break;
}
case 0x0026: // LD R[U:V] i //
{
const uint16_t i = (word0_first_half >> 12) & 0XF; // i000
const uint16_t j = (word0_first_half >> 8) & 0XF; // 0j00
const uint16_t ram_index_i = letter_code_to_ram_index(i);
const uint16_t ram_index_j = letter_code_to_ram_index(j);
int32_t array_span = ram[ram_index_j] - ram[ram_index_i];
for(int idx = 0; idx < array_span; idx++)
{
ram[ram[ram_index_i] + idx] = word1;
}
break;
}
case 0X0027: // LD REGISTERS TO VRAM W VRAM INDEX //
{
// syntax: LD R[U] R[i] R[j] R[k] R[l] //
const uint16_t i = (word0_first_half >> 12) & 0XF; // i000
const uint16_t ram_index_i = letter_code_to_ram_index(i);
const uint16_t idx_to_vram_idx = (rom[pc - 1] >> 16) & 0xFFFF;
const uint16_t width_sprite = (rom[pc - 1] >> 8) & 0XFF;
const uint16_t height_sprite = (rom[pc - 1]) & 0xFF;
const uint16_t vram_idx = ram[idx_to_vram_idx];
for(uint16_t h = 0; h < ram[height_sprite]; h++)
{
arraySliceAssignment(
ram, rom, vram_idx + (h*160),
ram[ram_index_i] + h*ram[width_sprite],
ram[width_sprite]
);
}
break;
}
case 0x0028: // LD R[i] R[U] //
{
const uint16_t i = (word1_first_half >> 12) & 0XF; // i000
const uint16_t ram_index_i = letter_code_to_ram_index(i);
ram[word0_first_half] = ram[ram[ram_index_i]];
break;
}
case 0x0029: // POP //
{
int a = STACK_FRAME_SIZE * (0 + sp);
int b = STACK_FRAME_SIZE * (1 + sp);
for(int x = 0; x < b; x++) ram[0 + x] = ram[a + x];
// pop from stack and don't change pc
sp -= 1;
break;
}
case 0x002a: // PUSH //
{
stack[sp] = pc;
int a = STACK_FRAME_SIZE * (0 + sp);
int b = STACK_FRAME_SIZE * (1 + sp);
for(int x = 0; x < b; x++) ram[a + x] = ram[0 + x];
sp += 1; // increment stack pointer
break;
}
case 0X002b: // INPUT //
{
SDL_PumpEvents();
const uint8_t* key = SDL_GetKeyboardState(NULL);
uint32_t word = 0x0;
if(key[SDL_SCANCODE_UP]) word |= (1 << 0);
if(key[SDL_SCANCODE_LEFT]) word |= (1 << 1);
if(key[SDL_SCANCODE_DOWN]) word |= (1 << 2);
if(key[SDL_SCANCODE_RIGHT]) word |= (1 << 3);
if(key[SDL_SCANCODE_Z]) word |= (1 << 4);
if(key[SDL_SCANCODE_X]) word |= (1 << 5);
if(key[SDL_SCANCODE_END]) word |= (1 << 6);
if(key[SDL_SCANCODE_ESCAPE]) word |= (1 << 7);
ram[word0_first_half] = word;
break;
}
case 0X002c: // SHT //
{
// syntax: SHT R[X] R[Y] k (shift right, and)
const uint32_t button = (ram[word1_first_half] >> word1_second_half) & 0x1;
ram[word0_first_half] = button;
break;
}
case 0x002d: // WAIT //
{
const uint32_t wait = 17;
SDL_Delay(wait);
break;
}
case 0X002e: // REGISTER TO REGISTER REMAINDER //
{
ram[word0_first_half] %= ram[word1];
break;
}
case 0X002f: // DIRECT REMAINDER //
{
ram[word0_first_half] %= word1;
break;
}
case 0x00ff: // EXIT //
{
done = true;
break;
}
default:
{
printf("error: caught unknown instruction 0x%04X\n", word0_second_half);
exit(1);
}
}
}
fclose(fp);
SDL_DestroyWindow(window);
SDL_DestroyRenderer(renderer);
SDL_DestroyTexture(texture);
}