init commitHEADmaster

1 files changed, 107 insertions, 0 deletions

diff --git a/turing.c b/turing.c
new file mode 100644
index 0000000..4061a39
--- /dev/null
+++ b/turing.c
@@ -0,0 +1,107 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+
+typedef struct node {
+	int id;
+	bool end;
+} node;
+
+typedef struct connection {
+	node *parrent;
+	char input;
+	char output;
+	int offset;
+	node *result;
+} connection;
+
+node nodes[128];
+int nodecount = 0;
+
+connection connections[1024];
+int connectioncount = 0;
+
+void perror(const char *msg) {
+	fprintf(stderr, "%s\n", msg);
+	exit(1);
+}
+
+node *findnode(int id) {
+	for (int i = 0; i < nodecount; i++)
+		if (nodes[i].id == id) return &nodes[i];
+	return NULL;
+}
+
+int main(int argc, char **argv) {
+	if (argc <= 1) perror("no file given");
+
+	FILE *f = fopen(argv[1], "r");
+	if (f == NULL) perror("failed to open file");
+
+	/* define nodes */
+	char *line = malloc(128);
+	while (fgets(line, 128, f)[0] == '#') continue; /* handles comments */
+
+	char *tok = strtok(line, " ");
+	while (tok != NULL) {
+		if (tok[0] == 'e') { 
+			nodes[nodecount].end = true;
+			tok++;
+		}
+		nodes[nodecount].id = atoi(tok);
+		nodecount++;
+		tok = strtok(NULL, " ");
+	}
+
+	/* define connections */
+	node *parrent, *result;
+comment:
+	while (fgets(line, 128, f) != NULL) {
+		if (line[0] == '#' || line[0] == '\n') goto comment;
+
+		char *tok = strtok(line, " ");
+		if ((parrent = findnode(atoi(tok))) == NULL) perror("unknown node specified");
+		connections[connectioncount].parrent = parrent;
+
+		tok = strtok(NULL, " ");
+		if (tok[0] == '#') connections[connectioncount].input = 0;
+		else connections[connectioncount].input = tok[0];
+
+		tok = strtok(NULL, " ");
+		if (tok[0] == '#') connections[connectioncount].output = 0;
+		else connections[connectioncount].output = tok[0];
+
+		tok = strtok(NULL, " ");
+		connections[connectioncount].offset = atoi(tok);
+
+		tok = strtok(NULL, " ");
+		if ((result = findnode(atoi(tok))) == NULL) perror("unknown node specified");
+		connections[connectioncount].result = result;
+
+		connectioncount++;
+	}
+
+	char tape[4096] = {0};
+	if (argc >= 3) strcat(tape, argv[2]); /* fill the tape with user input, if they give it */
+
+	char *head = tape;
+	node *current = &nodes[0];		
+	
+	for (;;) {
+success:
+		for (int i = 0; i < connectioncount; i++) {
+			if (connections[i].parrent == current && connections[i].input == *head){
+				*head = connections[i].output;
+				current = connections[i].result;
+				head += connections[i].offset;
+				goto success;
+			}
+		}
+		printf("%s\n", tape);
+		printf("%s\n", (current->end) ? "accept" : "reject"); /* did it end in a valid location */
+		break;
+	}
+		
+	return 0;
+}