initial

Makefile

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+CFLAGS=-O2 -Wall
+SRC=main.c interactive.c
+HEADER=interactive.h
+OUT=bfuck
+
+$(OUT): $(SRC) $(HEADER)
+	$(CC) $(SRC) $(CFLAGS) -o $(OUT)
+

README.md

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+# Brainfuck Interpreter
+Written in C. Nothing really interesting. Only distinct feature is interactive mode
+
+`hw.bf` and `hw_2.bf` are hello world code examples in brainfuck.
+
+Build:
+```
+make
+```
+
+Interpret file:
+```
+./bfuck <file>
+```
+
+Interactive mode:
+```
+./bfuck
+```

hw.bf

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+>+++++++++[<++++++++>-]<.>+++++++[<++++>-]<+.+++++++..+++.>>>++++++++[<++++>-]
+<.>>>++++++++++[<+++++++++>-]<---.<<<<.+++.------.--------.>>+.>++++++++++.

hw_2.bf

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+ ++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++
+ .>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.
+ ------.--------.>+.>.

interactive.c

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+// interactive.c
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+
+#include "interactive.h"
+
+void start_interactive()
+{
+    char* code = NULL;
+    _Bool exit = false;
+
+    printf("Type 'q' to quit from interactive mode\n");
+
+    while (!exit) {
+        printf(">>> ");
+
+        code = read_code();
+        size_t code_len = strlen(code);
+
+        if (code[0] == 'q') {
+            exit = true;
+        } else {
+            run_code(code, code_len);
+            printf("\n");
+        }
+
+        free(code);
+    }
+}
+
+char* read_code()
+{
+    char* code_buffer = NULL;
+    size_t buf_size;
+
+    if (getline(&code_buffer, &buf_size, stdin) == -1) {
+        if (feof(stdin)) {
+            printf("\n");
+            exit(EXIT_SUCCESS);
+        } else {
+            perror("Error: Cannot getline()");
+            exit(EXIT_FAILURE);
+        } 
+    }
+
+    return code_buffer;
+}
+

interactive.h

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+// interative.h
+
+#include <stdio.h>
+
+#define CELL_COUNT 30000
+#define START_BUFFER_SIZE 2048
+
+char* read_code();
+void run_code(char* code, int code_len);
+void start_interactive();

main.c

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+// main.c
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "interactive.h"
+
+int main(int argc, char* argv[])
+{
+    if (argc < 2) {
+        start_interactive();
+        exit(EXIT_SUCCESS);
+    }
+
+    char* input = argv[1];
+    FILE* input_file = fopen(input, "r");
+
+    if (!input_file) {
+        fprintf(stderr, "Error: File \"%s\" doesn't exist\n", input);
+        exit(EXIT_FAILURE);
+    }
+
+    // Get size of file
+    fseek(input_file, 0L, SEEK_END);
+    int code_len = ftell(input_file);
+    fseek(input_file, 0L, SEEK_SET);
+
+    char* code_buffer = malloc(code_len);
+
+    fread(code_buffer, sizeof(char), code_len, input_file);
+    fclose(input_file);
+
+    run_code(code_buffer, code_len);
+
+    free(code_buffer);
+    return 0;
+}
+
+void run_code(char* code, int code_len)
+{
+    // Create cell array and set every cell to 0
+    char cells[CELL_COUNT];
+    memset(cells, 0, sizeof(cells));
+
+    int cell_i = 0; // current cell index
+    int b = 0; // bracket counter
+
+    // Start interpreting code
+    for (int i = 0; i < code_len; i++) {
+        switch (code[i]) {
+            case '>': cell_i++; break;
+            case '<': cell_i--; break;
+            case '+': cells[cell_i]++; break;
+            case '-': cells[cell_i]--; break;
+            case '.': putchar(cells[cell_i]); break;
+            case ',':
+                      cells[cell_i] = getchar();
+                      getchar(); // remove '\n' from stdin
+                      break;
+            case '[':
+                      if (cells[cell_i] != 0) continue;
+                      b++;
+
+                      while (b > 0) {
+                          switch (code[i]) {
+                              case '[': b++; break;
+                              case ']': b--; break;
+                          }
+
+                          // In case if matching brace wasnt found and we
+                          // got past the code_len
+                          if (++i > code_len) {
+                              break;
+                          }
+                      } 
+                      break;
+            case ']':
+                      if (cells[cell_i] == 0) continue;
+                      b++;
+
+                      while (b > 0) {
+                          switch (code[i]) {
+                              case ']': b++; break;
+                              case '[': b--; break;
+                          }
+
+                          if (--i < 0) {
+                              break;
+                          }
+                      } 
+                      break;
+            default:
+                      break;
+        }
+    }
+}
+