make init code much less sketchy

run.c

@@ -1,10 +1,8 @@
 /*
 Inference for Llama-2 Transformer model in pure C.
 
-Compile simply with:
-$ gcc -o run run.c
-Or if that doesn't work then:
-$ gcc -o run run.c -lm
+Example compile: (see README for more details)
+$ gcc -O3 -o run run.c -lm
 
 Then run with:
 $ ./run
@@ -402,16 +400,24 @@ int main(int argc, char *argv[]) {
         srand((unsigned int)current_time);
     }
 
-    // read in the config header
+    // read in the checkpoint .bin file
     Config config;
-    FILE *file = fopen(checkpoint, "rb");
-    if (!file) {
-        printf("Unable to open file!");
-        return 1;
+    TransformerWeights weights;
+    {
+        FILE *file = fopen(checkpoint, "rb");
+        if (!file) {
+            printf("Unable to open file!");
+            return 1;
+        }
+        // read in the config header
+        fread(&config, sizeof(Config), 1, file);
+        // read in the Transformer weights
+        malloc_weights(&weights, &config);
+        checkpoint_init_weights(&weights, &config, file);
+        fclose(file);
     }
-    fread(&config, sizeof(Config), 1, file);
 
-    // init the Tokenizer
+    // read in the tokenizer vocab
     char** vocab = (char**)malloc(config.vocab_size * sizeof(char*));
     {
         FILE *file = fopen("tokenizer.bin", "r");
@@ -427,14 +433,9 @@ int main(int argc, char *argv[]) {
             fread(vocab[i], len, 1, file);
             vocab[i][len] = '\0'; // add the string terminating token
         }
+        fclose(file);
     }
 
-    // create and init the Transformer
-    TransformerWeights weights;
-    malloc_weights(&weights, &config);
-    checkpoint_init_weights(&weights, &config, file);
-    fclose(file);
-
     // create and init the application RunState
     RunState state;
     malloc_run_state(&state, &config);
@@ -469,7 +470,7 @@ int main(int argc, char *argv[]) {
         pos++;
     }
     printf("\n");
-    
+
     // report our achieved tok/s
     clock_t end = clock();
     double elapsed = (double)(end - start) / CLOCKS_PER_SEC;