1 files changed, 149 insertions, 0 deletions
diff --git a/as.c b/as.c
new file mode 100644
index 0000000..47890f2
--- /dev/null
+++ b/as.c
@@ -0,0 +1,149 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "as.h"
+
+void gettoken(TOKEN* token, FILE* file) {
+  char i[10];
+  int a, b, c;
+  char line[30];
+  int res;
+
+  if (fgets(line, 30, file) == NULL) {
+    if (feof(file)) {
+      token->eof = true;
+      token->valid = true;
+    } else {
+      token->eof = false;
+      token->valid = true;
+    }
+  } else {
+    res = sscanf(line, "%s %x, %x, %x", i, &a, &b, &c);
+
+    if (!strncmp(i, "nop",    3)) token->i = NOP;
+    if (!strncmp(i, "subleq", 6)) token->i = SUBLEQ;
+    if (!strncmp(i, "sub",    3)) token->i = SUB;
+    if (!strncmp(i, "add",    3)) token->i = ADD;
+    if (!strncmp(i, "jmp",    3)) token->i = JMP;
+    if (!strncmp(i, "mov",    3)) token->i = MOV;
+    if (!strncmp(i, "beq",    3)) token->i = BEQ;
+    if (!strncmp(i, "not",    3)) token->i = NOT;
+    if (!strncmp(i, "halt",   4)) token->i = HALT;
+    if (!strncmp(i, "data",   4)) token->i = DATA;
+
+    token->args = res - 1;
+    token->a = a;
+    token->b = b;
+    token->c = c;
+    token->eof = false;
+    token->valid = true;
+  }
+}
+
+bool handletoken(FILE* file, int* pc, TOKEN* token) {
+  switch(token->i) {
+    case NOP:
+      if (token->args != 0) return false;
+      *pc += 3; out(file, Z, Z, *pc);
+      break;
+    case SUBLEQ:
+      switch (token->args) {
+        case 2:
+          *pc += 3; out(file, token->a, token->b, *pc);
+          break;
+        case 3:
+          *pc += 3; out(file, token->a, token->b, token->c);
+          break;
+        default:
+          return false;
+      }
+      break;
+    case SUB:
+      if (token->args != 2) return false;
+      *pc += 3; out(file, token->a, token->b, *pc);
+      break;
+    case ADD:
+      if (token->args != 2) return false;
+      *pc += 3; out(file, token->a, Z, *pc);
+      *pc += 3; out(file, Z, token->b, *pc);
+      *pc += 3; out(file, Z, Z, *pc);
+      break;
+    case MOV:
+      if (token->args != 2) return false;
+      *pc += 3; out(file, token->b, token->b, *pc);
+      *pc += 3; out(file, token->a, Z, *pc);
+      *pc += 3; out(file, Z, token->b, *pc);
+      *pc += 3; out(file, Z, Z, *pc);
+      break;
+    case BEQ:
+      if (token->args != 2) return false;
+      *pc += 3; out(file, token->b, Z, *pc + 3);
+      *pc += 3; out(file, Z, Z, *pc + 6);
+      *pc += 3; out(file, Z, Z, *pc);
+      *pc += 3; out(file, Z, token->b, token->c);
+      break;
+    case JMP:
+      if (token->args != 1) return false;
+      *pc += 3; out(file, Z, Z, token->a);
+      break;
+    case NOT:
+      if (token->args != 1) return false;
+      *pc += 3;
+      break;
+    case HALT:
+      *pc += 3; out(file, -1, -1, -1);
+      break;
+    case DATA:
+      *pc += 3; 
+      switch (token->args) {
+        case 0:
+          out(file, 0, 0, 0);
+          break;
+        case 1:
+          out(file, token->a, 0, 0);
+          break;
+        case 2:
+          out(file, token->a, token->b, 0);
+          break;
+        case 3:
+          out(file, token->a, token->b, token->c);
+      }
+  }
+  return true;
+}
+
+bool parse(TOKEN* token, FILE *out, FILE *in) {
+  int pc = PLEN;
+  int line = 0;
+
+  while(true) {
+    line++;
+    gettoken(token, in);
+    if (token->eof) break;
+    if (!token->valid || !handletoken(out, &pc, token)) {
+      fprintf(stderr, "Error parsing line %d\n", line);
+      return false;
+    }
+  }
+
+  return true;
+}
+
+int main(int argc, char** argv) {
+  if (argc < 3)
+    return 1;
+
+  int ret;
+  FILE *in = fopen(argv[1], "r"), *out = fopen(argv[2], "w");
+  TOKEN* token = malloc(sizeof(token));
+
+  preamble(out);
+  ret = parse(token, out, in);
+  postamble(out);
+
+  fclose(in);
+  fclose(out);
+  free(token);
+
+  return !ret;
+}