fast check for ascii

danielaparker · danielaparker · commit b87f98b19055 · 2026-07-02T04:07:09.000-04:00
diff --git a/include/jsoncons/utility/unicode_traits.hpp b/include/jsoncons/utility/unicode_traits.hpp
@@ -1154,12 +1154,7 @@ namespace unicode_traits {
         {
             if ((end - it) >= 8)
             {
-                uint64_t chunk;
-                std::memcpy(&chunk, it, 8);
-                if ((chunk & mask) == 0) {
-                   it += 8;
-                   continue;
-                }
+                while (true) JSONCONS_REPEAT8({if (JSONCONS_LIKELY((trailing_bytes_for_utf8[*it] == 0) && (*it >= 0x80 && *it < 0xC2))) ++it; else break;})
             }
             const std::size_t len = static_cast<std::size_t>(trailing_bytes_for_utf8[*it]) + 1;
             if (len > (std::size_t)(end - it))

Original file line number	Diff line number	Diff line change
`@@ -1154,12 +1154,7 @@ namespace unicode_traits {`
`1154`	`1154`	`{`
`1155`	`1155`	`if ((end - it) >= 8)`
`1156`	`1156`	`{`
`1157`		`- uint64_t chunk;`
`1158`		`- std::memcpy(&chunk, it, 8);`
`1159`		`- if ((chunk & mask) == 0) {`
`1160`		`- it += 8;`
`1161`		`- continue;`
`1162`		`- }`
	`1157`	`+ while (true) JSONCONS_REPEAT8({if (JSONCONS_LIKELY((trailing_bytes_for_utf8[it] == 0) && (it >= 0x80 && *it < 0xC2))) ++it; else break;})`
`1163`	`1158`	`}`
`1164`	`1159`	`const std::size_t len = static_cast<std::size_t>(trailing_bytes_for_utf8[*it]) + 1;`
`1165`	`1160`	`if (len > (std::size_t)(end - it))`