Check in the pristine copy of ICU 4.6...

icu46/source/common/unicode/utf8.h

+/*
+*******************************************************************************
+*
+*   Copyright (C) 1999-2009, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+*
+*******************************************************************************
+*   file name:  utf8.h
+*   encoding:   US-ASCII
+*   tab size:   8 (not used)
+*   indentation:4
+*
+*   created on: 1999sep13
+*   created by: Markus W. Scherer
+*/
+
+/**
+ * \file
+ * \brief C API: 8-bit Unicode handling macros
+ * 
+ * This file defines macros to deal with 8-bit Unicode (UTF-8) code units (bytes) and strings.
+ * utf8.h is included by utf.h after unicode/umachine.h
+ * and some common definitions.
+ *
+ * For more information see utf.h and the ICU User Guide Strings chapter
+ * (http://icu-project.org/userguide/strings.html).
+ *
+ * <em>Usage:</em>
+ * ICU coding guidelines for if() statements should be followed when using these macros.
+ * Compound statements (curly braces {}) must be used  for if-else-while... 
+ * bodies and all macro statements should be terminated with semicolon.
+ */
+
+#ifndef __UTF8_H__
+#define __UTF8_H__
+
+/* utf.h must be included first. */
+#ifndef __UTF_H__
+#   include "unicode/utf.h"
+#endif
+
+/* internal definitions ----------------------------------------------------- */
+
+/**
+ * \var utf8_countTrailBytes
+ * Internal array with numbers of trail bytes for any given byte used in
+ * lead byte position.
+ *
+ * This is internal since it is not meant to be called directly by external clients;
+ * however it is called by public macros in this file and thus must remain stable,
+ * and should not be hidden when other internal functions are hidden (otherwise
+ * public macros would fail to compile).
+ * @internal
+ */
+#ifdef U_UTF8_IMPL
+U_EXPORT const uint8_t 
+#elif defined(U_STATIC_IMPLEMENTATION) || defined(U_COMMON_IMPLEMENTATION)
+U_CFUNC const uint8_t
+#else
+U_CFUNC U_IMPORT const uint8_t /* U_IMPORT2? */ /*U_IMPORT*/ 
+#endif
+utf8_countTrailBytes[256];
+
+/**
+ * Count the trail bytes for a UTF-8 lead byte.
+ *
+ * This is internal since it is not meant to be called directly by external clients;
+ * however it is called by public macros in this file and thus must remain stable.
+ * @internal
+ */
+#define U8_COUNT_TRAIL_BYTES(leadByte) (utf8_countTrailBytes[(uint8_t)leadByte])
+
+/**
+ * Mask a UTF-8 lead byte, leave only the lower bits that form part of the code point value.
+ *
+ * This is internal since it is not meant to be called directly by external clients;
+ * however it is called by public macros in this file and thus must remain stable.
+ * @internal
+ */
+#define U8_MASK_LEAD_BYTE(leadByte, countTrailBytes) ((leadByte)&=(1<<(6-(countTrailBytes)))-1)
+
+/**
+ * Function for handling "next code point" with error-checking.
+ *
+ * This is internal since it is not meant to be called directly by external clients;
+ * however it is U_STABLE (not U_INTERNAL) since it is called by public macros in this
+ * file and thus must remain stable, and should not be hidden when other internal
+ * functions are hidden (otherwise public macros would fail to compile).
+ * @internal
+ */
+U_STABLE UChar32 U_EXPORT2
+utf8_nextCharSafeBody(const uint8_t *s, int32_t *pi, int32_t length, UChar32 c, UBool strict);
+
+/**
+ * Function for handling "append code point" with error-checking.
+ *
+ * This is internal since it is not meant to be called directly by external clients;
+ * however it is U_STABLE (not U_INTERNAL) since it is called by public macros in this
+ * file and thus must remain stable, and should not be hidden when other internal
+ * functions are hidden (otherwise public macros would fail to compile).
+ * @internal
+ */
+U_STABLE int32_t U_EXPORT2
+utf8_appendCharSafeBody(uint8_t *s, int32_t i, int32_t length, UChar32 c, UBool *pIsError);
+
+/**
+ * Function for handling "previous code point" with error-checking.
+ *
+ * This is internal since it is not meant to be called directly by external clients;
+ * however it is U_STABLE (not U_INTERNAL) since it is called by public macros in this
+ * file and thus must remain stable, and should not be hidden when other internal
+ * functions are hidden (otherwise public macros would fail to compile).
+ * @internal
+ */
+U_STABLE UChar32 U_EXPORT2
+utf8_prevCharSafeBody(const uint8_t *s, int32_t start, int32_t *pi, UChar32 c, UBool strict);
+
+/**
+ * Function for handling "skip backward one code point" with error-checking.
+ *
+ * This is internal since it is not meant to be called directly by external clients;
+ * however it is U_STABLE (not U_INTERNAL) since it is called by public macros in this
+ * file and thus must remain stable, and should not be hidden when other internal
+ * functions are hidden (otherwise public macros would fail to compile).
+ * @internal
+ */
+U_STABLE int32_t U_EXPORT2
+utf8_back1SafeBody(const uint8_t *s, int32_t start, int32_t i);
+
+/* single-code point definitions -------------------------------------------- */
+
+/**
+ * Does this code unit (byte) encode a code point by itself (US-ASCII 0..0x7f)?
+ * @param c 8-bit code unit (byte)
+ * @return TRUE or FALSE
+ * @stable ICU 2.4
+ */
+#define U8_IS_SINGLE(c) (((c)&0x80)==0)
+
+/**
+ * Is this code unit (byte) a UTF-8 lead byte?
+ * @param c 8-bit code unit (byte)
+ * @return TRUE or FALSE
+ * @stable ICU 2.4
+ */
+#define U8_IS_LEAD(c) ((uint8_t)((c)-0xc0)<0x3e)
+
+/**
+ * Is this code unit (byte) a UTF-8 trail byte?
+ * @param c 8-bit code unit (byte)
+ * @return TRUE or FALSE
+ * @stable ICU 2.4
+ */
+#define U8_IS_TRAIL(c) (((c)&0xc0)==0x80)
+
+/**
+ * How many code units (bytes) are used for the UTF-8 encoding
+ * of this Unicode code point?
+ * @param c 32-bit code point
+ * @return 1..4, or 0 if c is a surrogate or not a Unicode code point
+ * @stable ICU 2.4
+ */
+#define U8_LENGTH(c) \
+    ((uint32_t)(c)<=0x7f ? 1 : \
+        ((uint32_t)(c)<=0x7ff ? 2 : \
+            ((uint32_t)(c)<=0xd7ff ? 3 : \
+                ((uint32_t)(c)<=0xdfff || (uint32_t)(c)>0x10ffff ? 0 : \
+                    ((uint32_t)(c)<=0xffff ? 3 : 4)\
+                ) \
+            ) \
+        ) \
+    )
+
+/**
+ * The maximum number of UTF-8 code units (bytes) per Unicode code point (U+0000..U+10ffff).
+ * @return 4
+ * @stable ICU 2.4
+ */
+#define U8_MAX_LENGTH 4
+
+/**
+ * Get a code point from a string at a random-access offset,
+ * without changing the offset.
+ * The offset may point to either the lead byte or one of the trail bytes
+ * for a code point, in which case the macro will read all of the bytes
+ * for the code point.
+ * The result is undefined if the offset points to an illegal UTF-8
+ * byte sequence.
+ * Iteration through a string is more efficient with U8_NEXT_UNSAFE or U8_NEXT.
+ *
+ * @param s const uint8_t * string
+ * @param i string offset
+ * @param c output UChar32 variable
+ * @see U8_GET
+ * @stable ICU 2.4
+ */
+#define U8_GET_UNSAFE(s, i, c) { \
+    int32_t _u8_get_unsafe_index=(int32_t)(i); \
+    U8_SET_CP_START_UNSAFE(s, _u8_get_unsafe_index); \
+    U8_NEXT_UNSAFE(s, _u8_get_unsafe_index, c); \
+}
+
+/**
+ * Get a code point from a string at a random-access offset,
+ * without changing the offset.
+ * The offset may point to either the lead byte or one of the trail bytes
+ * for a code point, in which case the macro will read all of the bytes
+ * for the code point.
+ * If the offset points to an illegal UTF-8 byte sequence, then
+ * c is set to a negative value.
+ * Iteration through a string is more efficient with U8_NEXT_UNSAFE or U8_NEXT.
+ *
+ * @param s const uint8_t * string
+ * @param start starting string offset
+ * @param i string offset, must be start<=i<length
+ * @param length string length
+ * @param c output UChar32 variable, set to <0 in case of an error
+ * @see U8_GET_UNSAFE
+ * @stable ICU 2.4
+ */
+#define U8_GET(s, start, i, length, c) { \
+    int32_t _u8_get_index=(int32_t)(i); \
+    U8_SET_CP_START(s, start, _u8_get_index); \
+    U8_NEXT(s, _u8_get_index, length, c); \
+}
+
+/* definitions with forward iteration --------------------------------------- */
+
+/**
+ * Get a code point from a string at a code point boundary offset,
+ * and advance the offset to the next code point boundary.
+ * (Post-incrementing forward iteration.)
+ * "Unsafe" macro, assumes well-formed UTF-8.
+ *
+ * The offset may point to the lead byte of a multi-byte sequence,
+ * in which case the macro will read the whole sequence.
+ * The result is undefined if the offset points to a trail byte
+ * or an illegal UTF-8 sequence.
+ *
+ * @param s const uint8_t * string
+ * @param i string offset
+ * @param c output UChar32 variable
+ * @see U8_NEXT
+ * @stable ICU 2.4
+ */
+#define U8_NEXT_UNSAFE(s, i, c) { \
+    (c)=(uint8_t)(s)[(i)++]; \
+    if((uint8_t)((c)-0xc0)<0x35) { \
+        uint8_t __count=U8_COUNT_TRAIL_BYTES(c); \
+        U8_MASK_LEAD_BYTE(c, __count); \
+        switch(__count) { \
+        /* each following branch falls through to the next one */ \
+        case 3: \
+            (c)=((c)<<6)|((s)[(i)++]&0x3f); \
+        case 2: \
+            (c)=((c)<<6)|((s)[(i)++]&0x3f); \
+        case 1: \
+            (c)=((c)<<6)|((s)[(i)++]&0x3f); \
+        /* no other branches to optimize switch() */ \
+            break; \
+        } \
+    } \
+}
+
+/**
+ * Get a code point from a string at a code point boundary offset,
+ * and advance the offset to the next code point boundary.
+ * (Post-incrementing forward iteration.)
+ * "Safe" macro, checks for illegal sequences and for string boundaries.
+ *
+ * The offset may point to the lead byte of a multi-byte sequence,
+ * in which case the macro will read the whole sequence.
+ * If the offset points to a trail byte or an illegal UTF-8 sequence, then
+ * c is set to a negative value.
+ *
+ * @param s const uint8_t * string
+ * @param i string offset, must be i<length
+ * @param length string length
+ * @param c output UChar32 variable, set to <0 in case of an error
+ * @see U8_NEXT_UNSAFE
+ * @stable ICU 2.4
+ */
+#define U8_NEXT(s, i, length, c) { \
+    (c)=(uint8_t)(s)[(i)++]; \
+    if((c)>=0x80) { \
+        uint8_t __t1, __t2; \
+        if( /* handle U+1000..U+CFFF inline */ \
+            (0xe0<(c) && (c)<=0xec) && \
+            (((i)+1)<(length)) && \
+            (__t1=(uint8_t)((s)[i]-0x80))<=0x3f && \
+            (__t2=(uint8_t)((s)[(i)+1]-0x80))<= 0x3f \
+        ) { \
+            /* no need for (c&0xf) because the upper bits are truncated after <<12 in the cast to (UChar) */ \
+            (c)=(UChar)(((c)<<12)|(__t1<<6)|__t2); \
+            (i)+=2; \
+        } else if( /* handle U+0080..U+07FF inline */ \
+            ((c)<0xe0 && (c)>=0xc2) && \
+            ((i)<(length)) && \
+            (__t1=(uint8_t)((s)[i]-0x80))<=0x3f \
+        ) { \
+            (c)=(UChar)((((c)&0x1f)<<6)|__t1); \
+            ++(i); \
+        } else if(U8_IS_LEAD(c)) { \
+            /* function call for "complicated" and error cases */ \
+            (c)=utf8_nextCharSafeBody((const uint8_t *)s, &(i), (int32_t)(length), c, -1); \
+        } else { \
+            (c)=U_SENTINEL; \
+        } \
+    } \
+}
+
+/**
+ * Append a code point to a string, overwriting 1 to 4 bytes.
+ * The offset points to the current end of the string contents
+ * and is advanced (post-increment).
+ * "Unsafe" macro, assumes a valid code point and sufficient space in the string.
+ * Otherwise, the result is undefined.
+ *
+ * @param s const uint8_t * string buffer
+ * @param i string offset
+ * @param c code point to append
+ * @see U8_APPEND
+ * @stable ICU 2.4
+ */
+#define U8_APPEND_UNSAFE(s, i, c) { \
+    if((uint32_t)(c)<=0x7f) { \
+        (s)[(i)++]=(uint8_t)(c); \
+    } else { \
+        if((uint32_t)(c)<=0x7ff) { \
+            (s)[(i)++]=(uint8_t)(((c)>>6)|0xc0); \
+        } else { \
+            if((uint32_t)(c)<=0xffff) { \
+                (s)[(i)++]=(uint8_t)(((c)>>12)|0xe0); \
+            } else { \
+                (s)[(i)++]=(uint8_t)(((c)>>18)|0xf0); \
+                (s)[(i)++]=(uint8_t)((((c)>>12)&0x3f)|0x80); \
+            } \
+            (s)[(i)++]=(uint8_t)((((c)>>6)&0x3f)|0x80); \
+        } \
+        (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80); \
+    } \
+}
+
+/**
+ * Append a code point to a string, overwriting 1 to 4 bytes.
+ * The offset points to the current end of the string contents
+ * and is advanced (post-increment).
+ * "Safe" macro, checks for a valid code point.
+ * If a non-ASCII code point is written, checks for sufficient space in the string.
+ * If the code point is not valid or trail bytes do not fit,
+ * then isError is set to TRUE.
+ *
+ * @param s const uint8_t * string buffer
+ * @param i string offset, must be i<capacity
+ * @param capacity size of the string buffer
+ * @param c code point to append
+ * @param isError output UBool set to TRUE if an error occurs, otherwise not modified
+ * @see U8_APPEND_UNSAFE
+ * @stable ICU 2.4
+ */
+#define U8_APPEND(s, i, capacity, c, isError) { \
+    if((uint32_t)(c)<=0x7f) { \
+        (s)[(i)++]=(uint8_t)(c); \
+    } else if((uint32_t)(c)<=0x7ff && (i)+1<(capacity)) { \
+        (s)[(i)++]=(uint8_t)(((c)>>6)|0xc0); \
+        (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80); \
+    } else if((uint32_t)(c)<=0xd7ff && (i)+2<(capacity)) { \
+        (s)[(i)++]=(uint8_t)(((c)>>12)|0xe0); \
+        (s)[(i)++]=(uint8_t)((((c)>>6)&0x3f)|0x80); \
+        (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80); \
+    } else { \
+        (i)=utf8_appendCharSafeBody(s, (int32_t)(i), (int32_t)(capacity), c, &(isError)); \
+    } \
+}
+
+/**
+ * Advance the string offset from one code point boundary to the next.
+ * (Post-incrementing iteration.)
+ * "Unsafe" macro, assumes well-formed UTF-8.
+ *
+ * @param s const uint8_t * string
+ * @param i string offset
+ * @see U8_FWD_1
+ * @stable ICU 2.4
+ */
+#define U8_FWD_1_UNSAFE(s, i) { \
+    (i)+=1+U8_COUNT_TRAIL_BYTES((s)[i]); \
+}
+
+/**
+ * Advance the string offset from one code point boundary to the next.
+ * (Post-incrementing iteration.)
+ * "Safe" macro, checks for illegal sequences and for string boundaries.
+ *
+ * @param s const uint8_t * string
+ * @param i string offset, must be i<length
+ * @param length string length
+ * @see U8_FWD_1_UNSAFE
+ * @stable ICU 2.4
+ */
+#define U8_FWD_1(s, i, length) { \
+    uint8_t __b=(uint8_t)(s)[(i)++]; \
+    if(U8_IS_LEAD(__b)) { \
+        uint8_t __count=U8_COUNT_TRAIL_BYTES(__b); \
+        if((i)+__count>(length)) { \
+            __count=(uint8_t)((length)-(i)); \
+        } \
+        while(__count>0 && U8_IS_TRAIL((s)[i])) { \
+            ++(i); \
+            --__count; \
+        } \
+    } \
+}
+
+/**
+ * Advance the string offset from one code point boundary to the n-th next one,
+ * i.e., move forward by n code points.
+ * (Post-incrementing iteration.)
+ * "Unsafe" macro, assumes well-formed UTF-8.
+ *
+ * @param s const uint8_t * string
+ * @param i string offset
+ * @param n number of code points to skip
+ * @see U8_FWD_N
+ * @stable ICU 2.4
+ */
+#define U8_FWD_N_UNSAFE(s, i, n) { \
+    int32_t __N=(n); \
+    while(__N>0) { \
+        U8_FWD_1_UNSAFE(s, i); \
+        --__N; \
+    } \
+}
+
+/**
+ * Advance the string offset from one code point boundary to the n-th next one,
+ * i.e., move forward by n code points.
+ * (Post-incrementing iteration.)
+ * "Safe" macro, checks for illegal sequences and for string boundaries.
+ *
+ * @param s const uint8_t * string
+ * @param i string offset, must be i<length
+ * @param length string length
+ * @param n number of code points to skip
+ * @see U8_FWD_N_UNSAFE
+ * @stable ICU 2.4
+ */
+#define U8_FWD_N(s, i, length, n) { \
+    int32_t __N=(n); \
+    while(__N>0 && (i)<(length)) { \
+        U8_FWD_1(s, i, length); \
+        --__N; \
+    } \
+}
+
+/**
+ * Adjust a random-access offset to a code point boundary
+ * at the start of a code point.
+ * If the offset points to a UTF-8 trail byte,
+ * then the offset is moved backward to the corresponding lead byte.
+ * Otherwise, it is not modified.
+ * "Unsafe" macro, assumes well-formed UTF-8.
+ *
+ * @param s const uint8_t * string
+ * @param i string offset
+ * @see U8_SET_CP_START
+ * @stable ICU 2.4
+ */
+#define U8_SET_CP_START_UNSAFE(s, i) { \
+    while(U8_IS_TRAIL((s)[i])) { --(i); } \
+}
+
+/**
+ * Adjust a random-access offset to a code point boundary
+ * at the start of a code point.
+ * If the offset points to a UTF-8 trail byte,
+ * then the offset is moved backward to the corresponding lead byte.
+ * Otherwise, it is not modified.
+ * "Safe" macro, checks for illegal sequences and for string boundaries.
+ *
+ * @param s const uint8_t * string
+ * @param start starting string offset (usually 0)
+ * @param i string offset, must be start<=i
+ * @see U8_SET_CP_START_UNSAFE
+ * @stable ICU 2.4
+ */
+#define U8_SET_CP_START(s, start, i) { \
+    if(U8_IS_TRAIL((s)[(i)])) { \
+        (i)=utf8_back1SafeBody(s, start, (int32_t)(i)); \
+    } \
+}
+
+/* definitions with backward iteration -------------------------------------- */
+
+/**
+ * Move the string offset from one code point boundary to the previous one
+ * and get the code point between them.
+ * (Pre-decrementing backward iteration.)
+ * "Unsafe" macro, assumes well-formed UTF-8.
+ *
+ * The input offset may be the same as the string length.
+ * If the offset is behind a multi-byte sequence, then the macro will read
+ * the whole sequence.
+ * If the offset is behind a lead byte, then that itself
+ * will be returned as the code point.
+ * The result is undefined if the offset is behind an illegal UTF-8 sequence.
+ *
+ * @param s const uint8_t * string
+ * @param i string offset
+ * @param c output UChar32 variable
+ * @see U8_PREV
+ * @stable ICU 2.4
+ */
+#define U8_PREV_UNSAFE(s, i, c) { \
+    (c)=(uint8_t)(s)[--(i)]; \
+    if(U8_IS_TRAIL(c)) { \
+        uint8_t __b, __count=1, __shift=6; \
+\
+        /* c is a trail byte */ \
+        (c)&=0x3f; \
+        for(;;) { \
+            __b=(uint8_t)(s)[--(i)]; \
+            if(__b>=0xc0) { \
+                U8_MASK_LEAD_BYTE(__b, __count); \
+                (c)|=(UChar32)__b<<__shift; \
+                break; \
+            } else { \
+                (c)|=(UChar32)(__b&0x3f)<<__shift; \
+                ++__count; \
+                __shift+=6; \
+            } \
+        } \
+    } \
+}
+
+/**
+ * Move the string offset from one code point boundary to the previous one
+ * and get the code point between them.
+ * (Pre-decrementing backward iteration.)
+ * "Safe" macro, checks for illegal sequences and for string boundaries.
+ *
+ * The input offset may be the same as the string length.
+ * If the offset is behind a multi-byte sequence, then the macro will read
+ * the whole sequence.
+ * If the offset is behind a lead byte, then that itself
+ * will be returned as the code point.
+ * If the offset is behind an illegal UTF-8 sequence, then c is set to a negative value.
+ *
+ * @param s const uint8_t * string
+ * @param start starting string offset (usually 0)
+ * @param i string offset, must be start<i
+ * @param c output UChar32 variable, set to <0 in case of an error
+ * @see U8_PREV_UNSAFE
+ * @stable ICU 2.4
+ */
+#define U8_PREV(s, start, i, c) { \
+    (c)=(uint8_t)(s)[--(i)]; \
+    if((c)>=0x80) { \
+        if((c)<=0xbf) { \
+            (c)=utf8_prevCharSafeBody((const uint8_t *)s, start, &(i), c, -1); \
+        } else { \
+            (c)=U_SENTINEL; \
+        } \
+    } \
+}
+
+/**
+ * Move the string offset from one code point boundary to the previous one.
+ * (Pre-decrementing backward iteration.)
+ * The input offset may be the same as the string length.
+ * "Unsafe" macro, assumes well-formed UTF-8.
+ *
+ * @param s const uint8_t * string
+ * @param i string offset
+ * @see U8_BACK_1
+ * @stable ICU 2.4
+ */
+#define U8_BACK_1_UNSAFE(s, i) { \
+    while(U8_IS_TRAIL((s)[--(i)])) {} \
+}
+
+/**
+ * Move the string offset from one code point boundary to the previous one.
+ * (Pre-decrementing backward iteration.)
+ * The input offset may be the same as the string length.
+ * "Safe" macro, checks for illegal sequences and for string boundaries.
+ *
+ * @param s const uint8_t * string
+ * @param start starting string offset (usually 0)
+ * @param i string offset, must be start<i
+ * @see U8_BACK_1_UNSAFE
+ * @stable ICU 2.4
+ */
+#define U8_BACK_1(s, start, i) { \
+    if(U8_IS_TRAIL((s)[--(i)])) { \
+        (i)=utf8_back1SafeBody(s, start, (int32_t)(i)); \
+    } \
+}
+
+/**
+ * Move the string offset from one code point boundary to the n-th one before it,
+ * i.e., move backward by n code points.
+ * (Pre-decrementing backward iteration.)
+ * The input offset may be the same as the string length.
+ * "Unsafe" macro, assumes well-formed UTF-8.
+ *
+ * @param s const uint8_t * string
+ * @param i string offset
+ * @param n number of code points to skip
+ * @see U8_BACK_N
+ * @stable ICU 2.4
+ */
+#define U8_BACK_N_UNSAFE(s, i, n) { \
+    int32_t __N=(n); \
+    while(__N>0) { \
+        U8_BACK_1_UNSAFE(s, i); \
+        --__N; \
+    } \
+}
+
+/**
+ * Move the string offset from one code point boundary to the n-th one before it,
+ * i.e., move backward by n code points.
+ * (Pre-decrementing backward iteration.)
+ * The input offset may be the same as the string length.
+ * "Safe" macro, checks for illegal sequences and for string boundaries.
+ *
+ * @param s const uint8_t * string
+ * @param start index of the start of the string
+ * @param i string offset, must be start<i
+ * @param n number of code points to skip
+ * @see U8_BACK_N_UNSAFE
+ * @stable ICU 2.4
+ */
+#define U8_BACK_N(s, start, i, n) { \
+    int32_t __N=(n); \
+    while(__N>0 && (i)>(start)) { \
+        U8_BACK_1(s, start, i); \
+        --__N; \
+    } \
+}
+
+/**
+ * Adjust a random-access offset to a code point boundary after a code point.
+ * If the offset is behind a partial multi-byte sequence,
+ * then the offset is incremented to behind the whole sequence.
+ * Otherwise, it is not modified.
+ * The input offset may be the same as the string length.
+ * "Unsafe" macro, assumes well-formed UTF-8.
+ *
+ * @param s const uint8_t * string
+ * @param i string offset
+ * @see U8_SET_CP_LIMIT
+ * @stable ICU 2.4
+ */
+#define U8_SET_CP_LIMIT_UNSAFE(s, i) { \
+    U8_BACK_1_UNSAFE(s, i); \
+    U8_FWD_1_UNSAFE(s, i); \
+}
+
+/**
+ * Adjust a random-access offset to a code point boundary after a code point.
+ * If the offset is behind a partial multi-byte sequence,
+ * then the offset is incremented to behind the whole sequence.
+ * Otherwise, it is not modified.
+ * The input offset may be the same as the string length.
+ * "Safe" macro, checks for illegal sequences and for string boundaries.
+ *
+ * @param s const uint8_t * string
+ * @param start starting string offset (usually 0)
+ * @param i string offset, must be start<=i<=length
+ * @param length string length
+ * @see U8_SET_CP_LIMIT_UNSAFE
+ * @stable ICU 2.4
+ */
+#define U8_SET_CP_LIMIT(s, start, i, length) { \
+    if((start)<(i) && (i)<(length)) { \
+        U8_BACK_1(s, start, i); \
+        U8_FWD_1(s, i, length); \
+    } \
+}
+
+#endif