28 files changed, 642 insertions, 0 deletions
diff --git a/lib/alloc/bufalloc.c b/lib/alloc/bufalloc.c
new file mode 100644
index 0000000..a81f5b9
--- /dev/null
+++ b/lib/alloc/bufalloc.c
@@ -0,0 +1,29 @@
+#include <errno.h>
+#if __has_include(<stdckdint.h>)
+#	include <stdckdint.h>
+#	warning "stdckdint.h now available; remove manual ckd_*() implementations"
+#elifdef __GNUC__
+#	define ckd_add(r, a, b) ((bool)__builtin_add_overflow(a, b, r))
+#	define ckd_mul(r, a, b) ((bool)__builtin_mul_overflow(a, b, r))
+#else
+#	define ckd_add(r, a, b) (*(r) = (a) + (b))
+#	define ckd_mul(r, a, b) (*(r) = (a) * (b))
+#	warning "ckd_*() not supported on the current platform"
+#endif
+#include <stdlib.h>
+
+#include "alloc.h"
+#include "errors.h"
+
+void *
+bufalloc(void *p, size_t n, size_t m)
+{
+	if (ckd_mul(&n, n, m)) {
+		errno = EOVERFLOW;
+		err(__func__);
+	}
+
+	if (!(p = realloc(p, n)))
+		err(__func__);
+	return p;
+}
diff --git a/lib/bob/u8strfit.c b/lib/bob/u8strfit.c
new file mode 100644
index 0000000..332a5d7
--- /dev/null
+++ b/lib/bob/u8strfit.c
@@ -0,0 +1,9 @@
+#include <stdlib.h>
+
+#include "bob.h"
+
+struct u8str *
+u8strfit(struct u8str *b)
+{
+	return (b->p = realloc(b->p, b->len)) ? b : nullptr;
+}
diff --git a/lib/bob/u8strfree.c b/lib/bob/u8strfree.c
new file mode 100644
index 0000000..7e25ca8
--- /dev/null
+++ b/lib/bob/u8strfree.c
@@ -0,0 +1,9 @@
+#include <stdlib.h>
+
+#include "bob.h"
+
+void
+u8strfree(struct u8str b)
+{
+	free(b.p);
+}
diff --git a/lib/bob/u8strgrow.c b/lib/bob/u8strgrow.c
new file mode 100644
index 0000000..f1f86d3
--- /dev/null
+++ b/lib/bob/u8strgrow.c
@@ -0,0 +1,39 @@
+#include <stdlib.h>
+
+#include "bob.h"
+
+static size_t nextpow2(size_t);
+
+struct u8str *
+u8strgrow(struct u8str *b, size_t n)
+{
+	if (n > b->cap) {
+		b->cap = nextpow2(n);
+		if (!(b->p = realloc(b->p, b->cap)))
+			return nullptr;
+	}
+	return b;
+}
+
+size_t
+nextpow2(size_t x)
+{
+#if defined(__has_builtin) && __has_builtin(__builtin_clzl)
+	x = x <= 1 ? 1 : 1 << (64 - __builtin_clzl(x - 1));
+#else
+	if (x) {
+		x--;
+		x |= x >> 1;
+		x |= x >> 2;
+		x |= x >> 4;
+		x |= x >> 8;
+		if (sizeof(size_t) >= 4)
+			x |= x >> 16;
+		if (sizeof(size_t) >= 8)
+			x |= x >> 32;
+	}
+	x++;
+#endif
+
+	return x;
+}
diff --git a/lib/bob/u8strinit.c b/lib/bob/u8strinit.c
new file mode 100644
index 0000000..60423c1
--- /dev/null
+++ b/lib/bob/u8strinit.c
@@ -0,0 +1,16 @@
+#include <stdlib.h>
+
+#include "bob.h"
+
+struct u8str *
+u8strinit(struct u8str *b, size_t n)
+{
+	if (n) {
+		if (!(b->p = malloc(n)))
+			return nullptr;
+	} else
+		b->p = nullptr;
+	b->len = 0;
+	b->cap = n;
+	return b;
+}
diff --git a/lib/bob/u8strpushr.c b/lib/bob/u8strpushr.c
new file mode 100644
index 0000000..6fe5fd9
--- /dev/null
+++ b/lib/bob/u8strpushr.c
@@ -0,0 +1,11 @@
+#include "bob.h"
+#include "mbstring.h"
+
+struct u8str *
+u8strpushr(struct u8str *b, rune ch)
+{
+	if (!u8strgrow(b, b->len + rtou8(nullptr, ch, 0)))
+		return nullptr;
+	b->len += rtou8(b->p + b->len, ch, b->cap - b->len);
+	return b;
+}
diff --git a/lib/bob/u8strpushstr.c b/lib/bob/u8strpushstr.c
new file mode 100644
index 0000000..64b123d
--- /dev/null
+++ b/lib/bob/u8strpushstr.c
@@ -0,0 +1,9 @@
+#include <string.h>
+
+#include "bob.h"
+
+struct u8str *
+u8strpushstr(struct u8str *b, const char *s)
+{
+	return u8strpushu8(b, (struct u8view){.p = s, .len = strlen(s)});
+}
diff --git a/lib/bob/u8strpushu8.c b/lib/bob/u8strpushu8.c
new file mode 100644
index 0000000..8358e01
--- /dev/null
+++ b/lib/bob/u8strpushu8.c
@@ -0,0 +1,14 @@
+#include <string.h>
+
+#include "bob.h"
+#include "mbstring.h"
+
+struct u8str *
+u8strpushu8(struct u8str *b, struct u8view v)
+{
+	if (!u8strgrow(b, b->len + v.len))
+		return nullptr;
+	memcpy(b->p + b->len, v.p, v.len);
+	b->len += v.len;
+	return b;
+}
diff --git a/lib/errors/cerr.c b/lib/errors/cerr.c
new file mode 100644
index 0000000..bf5a98d
--- /dev/null
+++ b/lib/errors/cerr.c
@@ -0,0 +1,14 @@
+#include <stdarg.h>
+#include <stdlib.h>
+
+#include "errors.h"
+
+void
+cerr(int code, const char *fmt, ...)
+{
+	va_list ap;
+	va_start(ap, fmt);
+	vwarn(fmt, ap);
+	va_end(ap);
+	exit(code);
+}
diff --git a/lib/errors/cerrx.c b/lib/errors/cerrx.c
new file mode 100644
index 0000000..b614f47
--- /dev/null
+++ b/lib/errors/cerrx.c
@@ -0,0 +1,14 @@
+#include <stdarg.h>
+#include <stdlib.h>
+
+#include "errors.h"
+
+void
+cerrx(int code, const char *fmt, ...)
+{
+	va_list ap;
+	va_start(ap, fmt);
+	vwarnx(fmt, ap);
+	va_end(ap);
+	exit(code);
+}
diff --git a/lib/errors/err.c b/lib/errors/err.c
new file mode 100644
index 0000000..906e661
--- /dev/null
+++ b/lib/errors/err.c
@@ -0,0 +1,14 @@
+#include <stdarg.h>
+#include <stdlib.h>
+
+#include "errors.h"
+
+void
+err(const char *fmt, ...)
+{
+	va_list ap;
+	va_start(ap, fmt);
+	vwarn(fmt, ap);
+	va_end(ap);
+	exit(EXIT_FAILURE);
+}
diff --git a/lib/errors/errx.c b/lib/errors/errx.c
new file mode 100644
index 0000000..1fd55af
--- /dev/null
+++ b/lib/errors/errx.c
@@ -0,0 +1,14 @@
+#include <stdarg.h>
+#include <stdlib.h>
+
+#include "errors.h"
+
+void
+errx(const char *fmt, ...)
+{
+	va_list ap;
+	va_start(ap, fmt);
+	vwarnx(fmt, ap);
+	va_end(ap);
+	exit(EXIT_FAILURE);
+}
diff --git a/lib/errors/setprogname.c b/lib/errors/setprogname.c
new file mode 100644
index 0000000..ab2de3e
--- /dev/null
+++ b/lib/errors/setprogname.c
@@ -0,0 +1,12 @@
+#include <string.h>
+
+#include "errors.h"
+
+const char *__mlib_errors_progname;
+
+void
+setprogname(const char *s)
+{
+	const char *p = strrchr(s, '/');
+	__mlib_errors_progname = p ? p + 1 : s;
+}
diff --git a/lib/errors/vwarn.c b/lib/errors/vwarn.c
new file mode 100644
index 0000000..bc6bd16
--- /dev/null
+++ b/lib/errors/vwarn.c
@@ -0,0 +1,15 @@
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "errors.h"
+
+void
+vwarn(const char *fmt, va_list ap)
+{
+	int save = errno;
+	fprintf(stderr, "%s: ", progname());
+	vfprintf(stderr, fmt, ap);
+	fprintf(stderr, ": %s\n", strerror(save));
+}
diff --git a/lib/errors/vwarnx.c b/lib/errors/vwarnx.c
new file mode 100644
index 0000000..72d8fa7
--- /dev/null
+++ b/lib/errors/vwarnx.c
@@ -0,0 +1,12 @@
+#include <stdarg.h>
+#include <stdio.h>
+
+#include "errors.h"
+
+void
+vwarnx(const char *fmt, va_list ap)
+{
+	fprintf(stderr, "%s: ", progname());
+	vfprintf(stderr, fmt, ap);
+	fputc('\n', stderr);
+}
diff --git a/lib/errors/warn.c b/lib/errors/warn.c
new file mode 100644
index 0000000..78f3e36
--- /dev/null
+++ b/lib/errors/warn.c
@@ -0,0 +1,12 @@
+#include <stdarg.h>
+
+#include "errors.h"
+
+void
+warn(const char *fmt, ...)
+{
+	va_list ap;
+	va_start(ap, fmt);
+	vwarn(fmt, ap);
+	va_end(ap);
+}
diff --git a/lib/errors/warnx.c b/lib/errors/warnx.c
new file mode 100644
index 0000000..ea50299
--- /dev/null
+++ b/lib/errors/warnx.c
@@ -0,0 +1,12 @@
+#include <stdarg.h>
+
+#include "errors.h"
+
+void
+warnx(const char *fmt, ...)
+{
+	va_list ap;
+	va_start(ap, fmt);
+	vwarnx(fmt, ap);
+	va_end(ap);
+}
diff --git a/lib/mbstring/rtou8.c b/lib/mbstring/rtou8.c
new file mode 100644
index 0000000..0ddac89
--- /dev/null
+++ b/lib/mbstring/rtou8.c
@@ -0,0 +1,37 @@
+#include <stddef.h>
+
+#include "mbstring.h"
+#include "rune.h"
+
+int
+rtou8(char8_t *s, rune ch, size_t n)
+{
+	if (ch <= U8_1B_MAX) {
+		if (n >= 1)
+			s[0] = ch;
+		return 1;
+	} else if (ch <= U8_2B_MAX) {
+		if (n >= 2) {
+			s[0] = (ch >> 6) | 0xC0;
+			s[1] = (ch & 0x3F) | 0x80;
+		}
+		return 2;
+	} else if (ch <= U8_3B_MAX) {
+		if (n >= 3) {
+			s[0] = (ch >> 12) | 0xE0;
+			s[1] = ((ch >> 6) & 0x3F) | 0x80;
+			s[2] = (ch & 0x3F) | 0x80;
+		}
+		return 3;
+	} else if (ch <= U8_4B_MAX) {
+		if (n >= 4) {
+			s[0] = (ch >> 18) | 0xF0;
+			s[1] = ((ch >> 12) & 0x3F) | 0x80;
+			s[2] = ((ch >> 6) & 0x3F) | 0x80;
+			s[3] = (ch & 0x3F) | 0x80;
+		}
+		return 4;
+	}
+
+	return rtou8(s, RUNE_ERROR, n);
+}
diff --git a/lib/mbstring/u8chk.c b/lib/mbstring/u8chk.c
new file mode 100644
index 0000000..79ef5ee
--- /dev/null
+++ b/lib/mbstring/u8chk.c
@@ -0,0 +1,19 @@
+#include "rune.h"
+#define _RUNE_NO_MACRO_WRAPPER 1
+#include "mbstring.h"
+
+char8_t *
+u8chk(const char8_t *s, size_t n)
+{
+	while (n) {
+		rune ch;
+		int m = u8tor(&ch, s);
+
+		if (ch == RUNE_ERROR)
+			return (char8_t *)s;
+		n -= m;
+		s += m;
+	}
+
+	return nullptr;
+}
diff --git a/lib/mbstring/u8chr.c b/lib/mbstring/u8chr.c
new file mode 100644
index 0000000..008b7d7
--- /dev/null
+++ b/lib/mbstring/u8chr.c
@@ -0,0 +1,97 @@
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#define _RUNE_NO_MACRO_WRAPPER 1
+#include "mbstring.h"
+
+/* NOTE: The memmem*() functions were taken directly from the memmem()
+   implementation on OpenBSD.  As a result, these functions are licensed under
+   OpenBSDs 2-Clause BSD License instead of this libraries 0-Clause BSD License.
+
+   The license for these functions is as follows:
+
+       Copyright © 2005–2020 Rich Felker, et al.
+
+       Permission is hereby granted, free of charge, to any person obtaining
+       a copy of this software and associated documentation files (the
+       “Software”), to deal in the Software without restriction, including
+       without limitation the rights to use, copy, modify, merge, publish,
+       distribute, sublicense, and/or sell copies of the Software, and to
+       permit persons to whom the Software is furnished to do so, subject to
+       the following conditions:
+
+       The above copyright notice and this permission notice shall be
+       included in all copies or substantial portions of the Software.
+
+       THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND,
+       EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+       MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+       IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+       CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+       TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+       SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
+
+static char8_t *
+memmem2(const char8_t *h, size_t k, const char8_t *n)
+{
+	uint16_t hw, nw;
+	hw = h[0] << 8 | h[1];
+	nw = n[0] << 8 | n[1];
+
+	for (h += 2, k -= 2; k; k--, hw = hw << 8 | *h++) {
+		if (hw == nw)
+			return (char8_t *)h - 2;
+	}
+	return hw == nw ? (char8_t *)h - 2 : nullptr;
+}
+
+static char8_t *
+memmem3(const char8_t *h, size_t k, const char8_t *n)
+{
+	uint32_t hw, nw;
+	hw = h[0] << 24 | h[1] << 16 | h[2] << 8;
+	nw = n[0] << 24 | n[1] << 16 | n[2] << 8;
+
+	for (h += 3, k -= 3; k; k--, hw = (hw | *h++) << 8) {
+		if (hw == nw)
+			return (char8_t *)h - 3;
+	}
+	return hw == nw ? (char8_t *)h - 3 : nullptr;
+}
+
+static char8_t *
+memmem4(const char8_t *h, size_t k, const char8_t *n)
+{
+	uint32_t hw, nw;
+	hw = h[0] << 24 | h[1] << 16 | h[2] << 8 | h[3];
+	nw = n[0] << 24 | n[1] << 16 | n[2] << 8 | n[3];
+
+	for (h += 4, k -= 4; k; k--, hw = hw << 8 | *h++) {
+		if (hw == nw)
+			return (char8_t *)h - 4;
+	}
+	return hw == nw ? (char8_t *)h - 4 : nullptr;
+}
+
+char8_t *
+u8chr(const char8_t *s, rune ch, size_t n)
+{
+	char8_t buf[U8_LEN_MAX];
+	int m = rtou8(buf, ch, sizeof(buf));
+
+	if (n < (size_t)m)
+		return nullptr;
+	switch (m) {
+	case 1:
+		return memchr(s, ch, n);
+	case 2:
+		return memmem2(s, n, buf);
+	case 3:
+		return memmem3(s, n, buf);
+	case 4:
+		return memmem4(s, n, buf);
+	}
+
+	unreachable();
+}
diff --git a/lib/mbstring/u8cmp.c b/lib/mbstring/u8cmp.c
new file mode 100644
index 0000000..732896c
--- /dev/null
+++ b/lib/mbstring/u8cmp.c
@@ -0,0 +1,11 @@
+#include <string.h>
+
+#include "mbstring.h"
+
+int
+u8cmp(struct u8view x, struct u8view y)
+{
+	if (x.len != y.len)
+		return x.len > y.len ? +1 : -1;
+	return memcmp(x.p, y.p, x.len);
+}
diff --git a/lib/mbstring/u8cspn.c b/lib/mbstring/u8cspn.c
new file mode 100644
index 0000000..4892de4
--- /dev/null
+++ b/lib/mbstring/u8cspn.c
@@ -0,0 +1,18 @@
+#include "mbstring.h"
+
+size_t
+u8cspn(const char8_t *s, size_t n, const rune *p, size_t m)
+{
+	rune ch;
+	size_t k, l;
+
+	for (k = 0; (l = u8next(&ch, &s, &n)); k += l) {
+		for (size_t i = 0; i < m; i++) {
+			if (p[i] == ch)
+				goto found;
+		}
+	}
+
+found:
+	return k;
+}
diff --git a/lib/mbstring/u8len.c b/lib/mbstring/u8len.c
new file mode 100644
index 0000000..217ab66
--- /dev/null
+++ b/lib/mbstring/u8len.c
@@ -0,0 +1,10 @@
+#include "mbstring.h"
+
+size_t
+u8len(const char8_t *s, size_t n)
+{
+	size_t m = 0;
+	while (u8next(nullptr, &s, &n))
+		m++;
+	return m;
+}
diff --git a/lib/mbstring/u8next.c b/lib/mbstring/u8next.c
new file mode 100644
index 0000000..82d2ad7
--- /dev/null
+++ b/lib/mbstring/u8next.c
@@ -0,0 +1,16 @@
+#include "mbstring.h"
+
+int
+u8next(rune *ch, const char8_t **s, size_t *n)
+{
+	rune _;
+	int m = 0;
+
+	if (*n) {
+		m = u8tor(ch ? ch : &_, *s);
+		*n -= m;
+		*s += m;
+	}
+
+	return m;
+}
diff --git a/lib/mbstring/u8prev.c b/lib/mbstring/u8prev.c
new file mode 100644
index 0000000..507f7e1
--- /dev/null
+++ b/lib/mbstring/u8prev.c
@@ -0,0 +1,45 @@
+#include <stddef.h>
+
+#include "mbstring.h"
+#include "rune.h"
+
+int
+u8prev(rune *ch, const char8_t **p, const char8_t *start)
+{
+	int off;
+	const char8_t *s = *p;
+	ptrdiff_t d = s - start;
+
+	if (d <= 0) {
+		return 0;
+	} else if (U8_BYTE_1(s[-1])) {
+		if (ch)
+			*ch = s[-1];
+		off = 1;
+	} else if (d > 1 && U8_BYTE_C(s[-1]) && U8_BYTE_2(s[-2])) {
+		if (ch)
+			*ch = ((s[-2] & 0x1F) << 6) | (s[-1] & 0x3F);
+		off = 2;
+	} else if (d > 2 && U8_BYTE_C(s[-1]) && U8_BYTE_C(s[-2])
+			&& U8_BYTE_3(s[-3])) {
+		if (ch) {
+			*ch =
+				((s[-3] & 0x0F) << 12) | ((s[-2] & 0x3F) << 6) | (s[-1] & 0x3F);
+		}
+		off = 3;
+	} else if (d > 3 && U8_BYTE_C(s[-1]) && U8_BYTE_C(s[-2]) && U8_BYTE_C(s[-3])
+			&& U8_BYTE_4(s[-4])) {
+		if (ch) {
+			*ch = ((s[-4] & 0x07) << 18) | ((s[-3] & 0x3F) << 12)
+			    | ((s[-2] & 0x3F) << 6) | (s[-1] & 0x3F);
+		}
+		off = 4;
+	} else {
+		if (ch)
+			*ch = RUNE_ERROR;
+		off = 1;
+	}
+
+	*p -= off;
+	return off;
+}
diff --git a/lib/mbstring/u8rchr.c b/lib/mbstring/u8rchr.c
new file mode 100644
index 0000000..b92c323
--- /dev/null
+++ b/lib/mbstring/u8rchr.c
@@ -0,0 +1,87 @@
+#include <stddef.h>
+#include <stdint.h>
+
+#define _RUNE_NO_MACRO_WRAPPER 1
+#include "mbstring.h"
+
+static char8_t *
+memrchr1(const char8_t *s, size_t k, const char8_t *n)
+{
+	for (const char8_t *p = s + k - 1; k-- > 0; p--) {
+		if (*p == *n)
+			return (char8_t *)p;
+	}
+	return nullptr;
+}
+
+static char8_t *
+memrchr2(const char8_t *h, size_t k, const char8_t *n)
+{
+	uint16_t hw, nw;
+	const char8_t *H = h + k - 1;
+	hw = H[-1] << 8 | H[-0];
+	nw = n[+0] << 8 | n[+1];
+
+	for (H -= 2, k -= 2; k; k--, hw = hw >> 8 | (*H-- << 8)) {
+		if (hw == nw)
+			return (char8_t *)H + 1;
+	}
+
+	return hw == nw ? (char8_t *)H + 1 : nullptr;
+}
+
+static char8_t *
+memrchr3(const char8_t *h, size_t k, const char8_t *n)
+{
+	uint32_t hw, nw;
+	const char8_t *H = h + k - 1;
+	hw = H[-2] << 24 | H[-1] << 16 | H[-0] << 8;
+	nw = n[+0] << 24 | n[+1] << 16 | n[+2] << 8;
+
+	for (H -= 3, k -= 3; k;
+	     k--, hw = (hw >> 8 | (*H-- << 24)) & UINT32_C(0xFFFFFF00))
+	{
+		if (hw == nw)
+			return (char8_t *)H + 1;
+	}
+
+	return hw == nw ? (char8_t *)H + 1 : nullptr;
+}
+
+static char8_t *
+memrchr4(const char8_t *h, size_t k, const char8_t *n)
+{
+	uint32_t hw, nw;
+	const char8_t *H = h + k - 1;
+	hw = H[-3] << 24 | H[-2] << 16 | H[-1] << 8 | H[-0];
+	nw = n[+0] << 24 | n[+1] << 16 | n[+2] << 8 | n[+3];
+
+	for (H -= 4, k -= 4; k; k--, hw = hw >> 8 | (*H-- << 24)) {
+		if (hw == nw)
+			return (char8_t *)H + 1;
+	}
+
+	return hw == nw ? (char8_t *)H + 1 : nullptr;
+}
+
+char8_t *
+u8rchr(const char8_t *s, rune ch, size_t n)
+{
+	char8_t buf[U8_LEN_MAX];
+	int m = rtou8(buf, ch, sizeof(buf));
+
+	if (n < (size_t)m)
+		return nullptr;
+	switch (m) {
+	case 1:
+		return (char8_t *)memrchr1(s, n, buf);
+	case 2:
+		return (char8_t *)memrchr2(s, n, buf);
+	case 3:
+		return (char8_t *)memrchr3(s, n, buf);
+	case 4:
+		return (char8_t *)memrchr4(s, n, buf);
+	}
+
+	unreachable();
+}
diff --git a/lib/mbstring/u8spn.c b/lib/mbstring/u8spn.c
new file mode 100644
index 0000000..1cf45f2
--- /dev/null
+++ b/lib/mbstring/u8spn.c
@@ -0,0 +1,22 @@
+#include "mbstring.h"
+
+size_t
+u8spn(const char8_t *s, size_t n, const rune *p, size_t m)
+{
+	rune ch;
+	size_t k = 0, l;
+
+	while ((l = u8next(&ch, &s, &n))) {
+		for (size_t i = 0; i < m; i++) {
+			if (p[i] == ch) {
+				k += l;
+				goto found;
+			}
+		}
+
+		break;
+found:;
+	}
+
+	return k;
+}
diff --git a/lib/mbstring/u8tor.c b/lib/mbstring/u8tor.c
new file mode 100644
index 0000000..85c4c19
--- /dev/null
+++ b/lib/mbstring/u8tor.c
@@ -0,0 +1,25 @@
+#include "mbstring.h"
+#include "rune.h"
+
+int
+u8tor(rune *ch, const char8_t *s)
+{
+	if (U8_BYTE_1(s[0])) {
+		*ch = s[0];
+		return 1;
+	} else if (U8_BYTE_2(s[0]) && U8_BYTE_C(s[1])) {
+		*ch = ((s[0] & 0x1F) << 6) | (s[1] & 0x3F);
+		return 2;
+	} else if (U8_BYTE_3(s[0]) && U8_BYTE_C(s[1]) && U8_BYTE_C(s[2])) {
+		*ch = ((s[0] & 0x0F) << 12) | ((s[1] & 0x3F) << 6) | (s[2] & 0x3F);
+		return 3;
+	} else if (U8_BYTE_4(s[0]) && U8_BYTE_C(s[1]) && U8_BYTE_C(s[2])
+				&& U8_BYTE_C(s[3])) {
+		*ch = ((s[0] & 0x07) << 18) | ((s[1] & 0x3F) << 12)
+		    | ((s[2] & 0x3F) << 6) | (s[3] & 0x3F);
+		return 4;
+	}
+
+	*ch = RUNE_ERROR;
+	return 1;
+}