1 files changed, 114 insertions, 0 deletions
diff --git a/homework/81568/BF_Interpreter/bf_interpreter.cpp b/homework/81568/BF_Interpreter/bf_interpreter.cpp
new file mode 100644
index 0000000..28d4c18
--- /dev/null
+++ b/homework/81568/BF_Interpreter/bf_interpreter.cpp
@@ -0,0 +1,114 @@
+#include "bf_interpreter.h"
+
+#include <cmath>
+#include <cstring>
+#include <iostream>
+#include <stack>
+
+#ifndef MEMSIZE
+#define MEMSIZE 30000
+#endif
+
+BFInterpreter::BFInterpreter(const char *program, std::istream &input, std::ostream &output) :
+  memory_blocks(nullptr), p(nullptr),
+  program(nullptr), input(input), output(output),
+  memory_size(MEMSIZE) {
+  
+  this->program = new char[strlen(program) + 1];
+  strncpy(this->program, program, strlen(program) + 1);
+  pp = this->program;
+
+  memory_blocks = new uchar[memory_size];
+  for (int i = 0; i < memory_size; ++i) {
+    memory_blocks[i] = 0;
+  }
+  p = memory_blocks;
+}
+
+BFInterpreter::~BFInterpreter() {
+  delete [] memory_blocks;
+  delete [] program;
+}
+
+void BFInterpreter::addMemory() {
+  uchar *new_memory = new uchar[memory_size + ((size_t) log2(memory_size))];
+  for (int i = 0; i < memory_size; ++i) {
+    new_memory[i] = memory_blocks[i];
+  }
+  delete [] memory_blocks;
+  memory_blocks = new_memory;
+  memory_size += log2(memory_size);
+}
+
+void BFInterpreter::compile() {
+  while (*pp) {
+    switch (*pp) {
+    case '[':
+      ++pp;
+      loop();
+      break;
+    case ']': // that will only happen if code is wrong
+      printf("Syntax error!\n");
+      return;
+    default:
+      proccessNonLoopCmd(*pp);
+    }
+    ++pp;
+  }
+  output.put('\n');
+}
+
+void BFInterpreter::loop() {
+  std::stack<char*> loops;
+  loops.push(pp);
+  
+  char *body = loops.top();
+  while (!loops.empty()) {
+    while (*body != ']' && *body != '[') {
+      proccessNonLoopCmd(*body);
+      ++body;
+    }
+    if (*body == ']') {
+      if (!*p) { /* End of a loop */
+        loops.pop();
+        ++body;
+      } else { /* Loop has not ended. Return to the beginning of the current loop */
+        body = loops.top();
+      }
+    } else { /* Start of a new loop */
+      loops.push(body + 1);
+      ++body;
+    }
+  }
+  pp = --body;
+  return;
+}
+
+void BFInterpreter::proccessNonLoopCmd(char c) {
+  switch (c) {
+  case '+':
+    ++*p;
+    break;
+  case '-':
+    --*p;
+    break;
+  case '.':
+    output.put(*p);
+    break;
+  case ',':
+    *p = input.get();
+    break;
+  case '<':
+    if (p == memory_blocks)
+      p = memory_blocks + (memory_size - 1);
+    else 
+      --p;
+    break;
+  case '>':
+    if (p == memory_blocks + (memory_size - 1))
+      p = memory_blocks;
+    else
+      ++p;
+    break;
+  }
+}