Buffer partial wide characters more efficiently: instead of storing the

multibyte representation in conversion state objects, store the
accumulated wide character, set number and number of bytes remaining
to avoid having to derive them every time mbrtowc() is called.

1 files changed, 46 insertions, 31 deletions

diff --git a/lib/libc/locale/euc.c b/lib/libc/locale/euc.c
index 3ecb633..746ddc1 100644
--- a/lib/libc/locale/euc.c
+++ b/lib/libc/locale/euc.c
@@ -62,8 +62,9 @@ typedef struct {
 } _EucInfo;
 
 typedef struct {
-	int	count;
-	u_char	bytes[MB_LEN_MAX];
+	wchar_t	ch;
+	int	set;
+	int	want;
 } _EucState;
 
 int
@@ -122,7 +123,7 @@ int
 _EUC_mbsinit(const mbstate_t *ps)
 {
 
-	return (ps == NULL || ((const _EucState *)ps)->count == 0);
+	return (ps == NULL || ((const _EucState *)ps)->want == 0);
 }
 
 #define	CEI	((_EucInfo *)(_CurrentRuneLocale->variable))
@@ -144,13 +145,14 @@ _EUC_mbrtowc(wchar_t * __restrict pwc, const char * __restrict s, size_t n,
     mbstate_t * __restrict ps)
 {
 	_EucState *es;
-	int len, ocount, remain, set;
+	int i, set, want;
 	wchar_t wc;
-	size_t ncopy;
+	const char *os;
 
 	es = (_EucState *)ps;
 
-	if (es->count < 0 || es->count > sizeof(es->bytes)) {
+	if (es->want < 0 || es->want > MB_CUR_MAX || es->set < 0 ||
+	    es->set > 3) {
 		errno = EINVAL;
 		return ((size_t)-1);
 	}
@@ -161,41 +163,54 @@ _EUC_mbrtowc(wchar_t * __restrict pwc, const char * __restrict s, size_t n,
 		pwc = NULL;
 	}
 
-	ncopy = MIN(MIN(n, MB_CUR_MAX), sizeof(es->bytes) - es->count);
-	memcpy(es->bytes + es->count, s, ncopy);
-	ocount = es->count;
-	es->count += ncopy;
-	s = (char *)es->bytes;
-	n = es->count;
-
-	if (n == 0 || (size_t)(len = CEI->count[set = _euc_set(*s)]) > n)
+	if (n == 0)
 		/* Incomplete multibyte sequence */
 		return ((size_t)-2);
-	wc = 0;
-	remain = len;
-	switch (set) {
-	case 3:
-	case 2:
-		--remain;
-		++s;
-		/* FALLTHROUGH */
-	case 1:
-	case 0:
-		wc = (unsigned char)*s++;
-		while (--remain > 0) {
+
+	os = s;
+
+	if (es->want == 0) {
+		want = CEI->count[set = _euc_set(*s)];
+		if (set == 2 || set == 3) {
+			--want;
+			if (--n == 0) {
+				/* Incomplete multibyte sequence */
+				es->set = set;
+				es->want = want;
+				es->ch = 0;
+				return ((size_t)-2);
+			}
+			++s;
 			if (*s == '\0') {
 				errno = EILSEQ;
 				return ((size_t)-1);
 			}
-			wc = (wc << 8) | (unsigned char)*s++;
 		}
-		break;
+		wc = (unsigned char)*s++;
+	} else {
+		set = es->set;
+		want = es->want;
+		wc = es->ch;
+	}
+	for (i = (es->want == 0) ? 1 : 0; i < MIN(want, n); i++) {
+		if (*s == '\0') {
+			errno = EILSEQ;
+			return ((size_t)-1);
+		}
+		wc = (wc << 8) | (unsigned char)*s++;
+	}
+	if (i < want) {
+		/* Incomplete multibyte sequence */
+		es->set = set;
+		es->want = want - i;
+		es->ch = wc;
+		return ((size_t)-2);
 	}
 	wc = (wc & ~CEI->mask) | CEI->bits[set];
 	if (pwc != NULL)
 		*pwc = wc;
-	es->count = 0;
-	return (wc == L'\0' ? 0 : len - ocount);
+	es->want = 0;
+	return (wc == L'\0' ? 0 : s - os);
 }
 
 size_t
@@ -207,7 +222,7 @@ _EUC_wcrtomb(char * __restrict s, wchar_t wc, mbstate_t * __restrict ps)
 
 	es = (_EucState *)ps;
 
-	if (es->count != 0) {
+	if (es->want != 0) {
 		errno = EINVAL;
 		return ((size_t)-1);
 	}