[post] AArch64 Bootstrapping 1

1 files changed, 32 insertions, 0 deletions

diff --git a/static/20240817-aarch64-bootstrapping-1/hex.c b/static/20240817-aarch64-bootstrapping-1/hex.c
new file mode 100644
index 0000000..aca16e2
--- /dev/null
+++ b/static/20240817-aarch64-bootstrapping-1/hex.c
@@ -0,0 +1,32 @@
+#include <stdio.h>
+
+int main(void) {
+  char c = 0;      // Input character
+  int count = 0;   // Hex digits parsed for this number
+  long long v = 0; // Current value
+
+  while ((c = getchar()) != EOF) {
+
+    // Skip comments
+    if (c == '\\') { while ((c = getchar()) != EOF && c != '\n') {} }
+
+    // Process incoming digits and add to running value
+    else if (('0' <= c) && (c <= '9')) { v = (v << 4) + (c - '0'); count++; }
+    else if (('a' <= c) && (c <= 'f')) { v = (v << 4) + (c - 'a' + 10); count++; }
+
+    // Send the finished number out the other end
+    else if (c == ' ') {
+
+      // Turn the number of hex digits into a number of bytes
+      if (count & 1) count++;
+      count >>= 1;
+
+      // Emit each byte, littlest first
+      for (; count>0; count--) {
+        c = v & 0xFF;
+        putchar(c);
+        v >>= 8;
+      }
+    }
+  }
+}