add lib.h/lib.c

1 files changed, 56 insertions, 0 deletions

diff --git a/02-usart/src/lib.c b/02-usart/src/lib.c
new file mode 100644
index 0000000..d5d81da
--- /dev/null
+++ b/02-usart/src/lib.c
@@ -0,0 +1,56 @@
+#include "lib.h"
+
+#define nybble_to_hex(n) \
+  ((n) < 10 ? 0x30 + (n) : ('A' + ((n) - 10)))
+
+void hexify(uint32_t v, char* into)
+{
+  into += 8;
+
+  *(into--) = 0;
+
+  *(into--) = nybble_to_hex(v & 0x0F);
+  v >>= 4;
+  *(into--) = nybble_to_hex(v & 0x0F);
+  v >>= 4;
+  *(into--) = nybble_to_hex(v & 0x0F);
+  v >>= 4;
+  *(into--) = nybble_to_hex(v & 0x0F);
+  v >>= 4;
+
+  *(into--) = nybble_to_hex(v & 0x0F);
+  v >>= 4;
+  *(into--) = nybble_to_hex(v & 0x0F);
+  v >>= 4;
+  *(into--) = nybble_to_hex(v & 0x0F);
+  v >>= 4;
+  *into = nybble_to_hex(v & 0x0F);
+  v >>= 4;
+}
+
+void decimalify(int v, char* into)
+{
+  int c = 0;
+  int i;
+
+  if (v == 0) {
+    *(into ++) = '0';
+    *into = 0;
+    return;
+  } else {
+    while (v > 0) {
+      *(into ++) = 0x30 + (v % 10);
+      v /= 10;
+      ++ c;
+    }
+  }
+  *into = 0;
+
+  into -= c;
+  for (i = 0; i < c / 2; ++ i) {
+    char tmp = into[i];
+    into[i] = into[c - i - 1];
+    into[c - i - 1] = tmp;
+  }
+
+}