[libc-commits] [libc] [libc] Add inet_ntop (PR #204143)

[Jeff Bailey via libc-commits]

================
@@ -61,5 +68,160 @@ cpp::optional<in_addr_t> inet_addr(const char *cp) {
   return Endian::to_big_endian(result);
 }
 
+namespace {
+
+size_t ipv4_num_bytes(cpp::span<const uint8_t> src) {
+  size_t result = 8; // four digits, three dots and '\0'
+  for (unsigned i = 0; i < 4; ++i)
+    result += (src[i] >= 10) + (src[i] >= 100);
+  return result;
+}
+
+size_t ipv4_to_str_unchecked(cpp::span<const uint8_t> src,
+                             cpp::span<char> dst) {
+  size_t pos = 0;
+  for (unsigned i = 0; i < 4; ++i) {
+    uint8_t val = src[i];
+    if (val >= 100) {
----------------
kaladron wrote:

Consider this:

```c++
if (val >= 100) {
            uint8_t cent = val / 100;
            uint8_t rem = val % 100; 
            
            dst[pos++] = '0' + cent;
            dst[pos++] = '0' + (rem / 10);
            dst[pos++] = '0' + (rem % 10);
        } else if (val >= 10) {
            dst[pos++] = '0' + (val / 10);
            dst[pos++] = '0' + (val % 10);
        } else {
            dst[pos++] = '0' + val;
        }
```

I think val can then be const, which makes this a bit easier to trace, and I think might optimise slightly better.

https://github.com/llvm/llvm-project/pull/204143