first commit

hex.c

@@ -0,0 +1,43 @@
+#include <stdio.h>
+
+// TODO: Error checking
+
+#define BYTES 1024
+#define BYTES_PER_LINE 10
+
+void print_hex(unsigned char* buf, int byteno)
+{
+  for (int i=0; i<byteno; i++)
+  {
+    if (i % BYTES_PER_LINE == 0)
+    {
+      puts("");
+    }
+    printf("%.2X ", buf[i]);
+  }
+  puts("");
+}
+
+void main(int argc, char** argv)
+{
+  FILE* f = fopen(argv[1], "r");
+  unsigned char buf[BYTES];
+  int byteno = fread(buf, 1, BYTES, f);
+  print_hex(buf, byteno);
+  
+  for (;;)
+  {
+    char cmd;
+    int loc;
+    scanf("%c%d", &cmd, &loc);
+
+    if (cmd == 'p') print_hex(buf + loc, BYTES_PER_LINE);
+    if (cmd == 'e') scanf("%x", buf + loc);
+    if (cmd == 's') break;
+  }
+
+  fclose(f);
+  f = fopen(argv[1], "w");
+  fwrite(buf, 1, BYTES, f);
+  fclose(f);
+}