1 files changed, 136 insertions, 0 deletions
diff --git a/src/interpreter.c b/src/interpreter.c
new file mode 100644
index 0000000..f14abcc
--- /dev/null
+++ b/src/interpreter.c
@@ -0,0 +1,136 @@
+#include "interpreter.h"
+#include "program.h"
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static void loop_end(Program* program) {
+    uint32_t count = 1;
+    Symbol s;
+
+    while (true) {
+        program_next(program, &s);
+        if (s == StartLoop) {
+            count++;
+        } else if (s == EndLoop) {
+            count--;
+        } else if (s == Eof) {
+            return;
+        }
+
+        if (count == 0) return;
+    }
+}
+
+static void loop_start(Program* program) {
+    uint32_t count = 1;
+    Symbol s;
+
+    program_last(program, &s);
+    while (true) {
+        program_last(program, &s);
+        if (s == StartLoop) {
+            count--;
+        } else if (s == EndLoop) {
+            count++;
+        } else if (s == Eof) {
+            return;
+        }
+
+        if (count == 0) {
+            return;
+        };
+    }
+}
+
+static void recurse_program(Program* program, Tape* tape) {
+    Symbol s;
+
+next:
+    program_next(program, &s);
+
+    switch (s) {
+        case MoveLeft:
+            tape_left(tape);
+            break;
+        case MoveRight:
+            tape_right(tape);
+            break;
+        case Increment:
+            tape_set(tape, tape_get(tape) + 1);
+            break;
+        case Decrement:
+            tape_set(tape, tape_get(tape) - 1);
+            break;
+        case StartLoop:
+            if (tape_get(tape) == 0)
+                loop_end(program);
+            break;
+        case EndLoop:
+            if (tape_get(tape) != 0)
+                loop_start(program);
+            break;
+        case PutChar: {
+            printf("%c", tape_get(tape));
+            break;
+        }
+        case GetChar: {
+            uint8_t c = (uint8_t) getchar();
+            tape_set(tape, c);
+            break;
+        }
+        case Allocate: {
+            uint8_t len = tape_get(tape);
+            Tape* new = malloc(sizeof(Tape));
+            tape_init(len, tape);
+            void* ptr = (void*) tape_ptr(tape);
+            memcpy(ptr, &new, sizeof(Tape*));
+            break;
+        }
+        case Free: {
+            Tape* old;
+            void* ptr = (void*) tape_ptr(tape);
+            memcpy(&old, ptr, sizeof(Tape*));
+            memset(ptr, 0, sizeof(Tape*));
+            free(old);
+            break;
+        }
+        case EnterTape: {
+            Tape* cur;
+            void* ptr = (void*) tape_ptr(tape);
+            memcpy(&cur, ptr, sizeof(Tape*));
+            recurse_program(program, cur);
+            break;
+        }
+        case GetString: {
+            uint8_t len = tape_get(tape);
+            void* ptr = (void*) tape_ptr(tape);
+            fgets(ptr, len, stdin);
+            break;
+        }
+        case PutString: {
+            char* ptr = (char*) tape_ptr(tape);
+            printf("%s", ptr);
+            break;
+        }
+        case Clear:
+            printf("\033c");
+            break;
+        case LeaveTape:
+        case Eof:
+        case Invalid:
+            return;
+    }
+
+    goto next;
+}
+
+void run_program(Program* program) {
+    Tape tape;
+    tape_init(sizeof(void*), &tape);
+    recurse_program(program, &tape);
+    tape_free(&tape);
+}