96 lines
2.8 KiB
C
96 lines
2.8 KiB
C
#include <stdio.h>
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#include <error.h>
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#include <stdlib.h>
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static unsigned char *data_start;
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static unsigned char *data_ptr;
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void process_command(char command, FILE *file) {
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switch(command) {
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case '>':
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/* increment the data pointer (to point to the next cell to the right). */
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++data_ptr;
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/* TODO : Check if over allocated memory */
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break;
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case '<':
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/* decrement the data pointer (to point to the next cell to the left). */
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--data_ptr;
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/* TODO : Check if under allocated memory */
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break;
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case '+':
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/* increment (increase by one) the byte at the data pointer. */
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++*data_ptr;
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break;
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case '-':
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/* decrement (decrease by one) the byte at the data pointer. */
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--*data_ptr;
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break;
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case '.':
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/* output a character, the ASCII value of which being the byte at the
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* data pointer. */
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putchar(*data_ptr);
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break;
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case ',':
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/* accept one byte of input, storing its value in the byte at the data
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* pointer. */
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*data_ptr = getchar();
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break;
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case '[':
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/* [ : if the byte at the data pointer is zero, then instead of moving the
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* instruction pointer forward to the next command, jump it forward to
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* the command after the matching ] command.
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* ] : if the byte at the data pointer is nonzero, then instead of moving
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* the instruction pointer forward to the next command, jump it back to
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* the command after the matching [ command. */
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{
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fpos_t position;
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fgetpos(file, &position);
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while(*data_ptr != 0) {
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fsetpos(file, &position);
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char c = getc(file);
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while( c!= ']' && c != EOF) {
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process_command(c, file);
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c = getc(file);
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}
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}
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}
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break;
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case ']':
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/* if we encounter one here, it means there are not balanced */
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fprintf(stderr, "Error in the source file, unbalanced ']'\n");
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exit(2);
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break;
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default:
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/* Brainfuck ignores all characters except the eight commands +-<>[],. */
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break;
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}
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}
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int main(int argc, char **argv)
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{
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data_start = calloc(30000, sizeof(char));
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data_ptr = data_start;
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if (argc > 1) {
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char command;
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FILE *file = fopen(argv[1], "r");
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if (!file) {
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fprintf(stderr, "Error: No such file %s\n", argv[1]);
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return 2;
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}
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while((command = getc(file)) != EOF) {
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process_command(command, file);
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}
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fclose(file);
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return 0;
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} else {
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fprintf(stderr, "Usage: %s source_file\n", argv[0]);
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return 1;
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}
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return 0;
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}
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