122 lines
2.7 KiB
Plaintext
122 lines
2.7 KiB
Plaintext
// Brainfuck Interpreter
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// Reads program from stdin, interprets and outputs to stdout.
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//
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// Main optimization targets:
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// jump table, inline variables, etc.
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int program_length = 0;
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int program[65536] = {};
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int tape[65536] = {};
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int input[65536] = {};
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int input_length = 0;
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int output[65536] = {};
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int output_length = 0;
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int get_bf_char() {
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int get = getch();
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while (get != 62 && get != 60 && get != 43 && get != 45 && get != 91 &&
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get != 93 && get != 46 && get != 44 && get != 35) {
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get = getch();
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}
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return get;
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}
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void read_program() {
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int get = get_bf_char();
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while (get != 35) {
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program[program_length] = get;
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get = get_bf_char();
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program_length = program_length + 1;
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}
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// read input
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// input starts with an `i`
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int verify = getch();
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if (verify != 105) {
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return;
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}
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// and a length
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input_length = getint();
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// and a random char
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getch();
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int i = 0;
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while (i < input_length) {
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input[i] = getch();
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i = i + 1;
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}
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}
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void run_program() {
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int ip = 0;
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int read_head = 0;
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int input_head = 0;
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int return_address[512] = {};
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int return_address_top = 0;
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output_length = 0;
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while (ip < program_length) {
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int code = program[ip];
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if (code == 62) {
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read_head = read_head + 1;
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} else if (code == 60) {
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read_head = read_head - 1;
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} else if (code == 43) {
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tape[read_head] = tape[read_head] + 1;
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} else if (code == 45) {
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tape[read_head] = tape[read_head] - 1;
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} else if (code == 91) {
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int val = tape[read_head];
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if (val != 0) {
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return_address[return_address_top] = ip;
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return_address_top = return_address_top + 1;
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} else {
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// find the matching ]
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int loop = 1;
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while (loop > 0) {
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ip = ip + 1;
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if (program[ip] == 93) {
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loop = loop - 1;
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}
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if (program[ip] == 91) {
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loop = loop + 1;
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}
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}
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}
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} else if (code == 93) {
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int val = tape[read_head];
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if (val == 0) {
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return_address_top = return_address_top - 1;
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} else {
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ip = return_address[return_address_top - 1];
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}
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} else if (code == 46) {
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output[output_length] = tape[read_head];
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output_length = output_length + 1;
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} else if (code == 44) {
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if (input_head >= input_length) {
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tape[read_head] = 0;
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} else {
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tape[read_head] = input[input_head];
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input_head = input_head + 1;
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}
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}
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ip = ip + 1;
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}
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}
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void output_() {
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int i = 0;
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while (i < output_length) {
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putch(output[i]);
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i = i + 1;
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}
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}
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int main() {
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read_program();
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starttime();
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run_program();
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stoptime();
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output_();
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return 0;
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}
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