The Tor Browser / file revision

 /*

 *******************************************************************************

 *

 *   Copyright (C) 1999-2013, 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.

  *

  * For more information see utf.h and the ICU User Guide Strings chapter

  * (http://userguide.icu-project.org/strings).

  *

  * <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__

 #include "unicode/umachine.h"

 #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];

 /**

  * Counts the trail bytes for a UTF-8 lead byte.

  * Returns 0 for 0..0xbf as well as for 0xfe and 0xff.

  *

  * 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.

  *

  * Note: Beginning with ICU 50, the implementation uses a multi-condition expression

  * which was shown in 2012 (on x86-64) to compile to fast, branch-free code.

  * leadByte is evaluated multiple times.

  *

  * The pre-ICU 50 implementation used the exported array utf8_countTrailBytes:

  * #define U8_COUNT_TRAIL_BYTES(leadByte) (utf8_countTrailBytes[leadByte])

  * leadByte was evaluated exactly once.

  *

  * @param leadByte The first byte of a UTF-8 sequence. Must be 0..0xff.

  * @internal

  */

 #define U8_COUNT_TRAIL_BYTES(leadByte) \

     ((leadByte)<0xf0 ? \

         ((leadByte)>=0xc0)+((leadByte)>=0xe0) : \

         (leadByte)<0xfe ? 3+((leadByte)>=0xf8)+((leadByte)>=0xfc) : 0)

 /**

  * Counts the trail bytes for a UTF-8 lead byte of a valid UTF-8 sequence.

  * The maximum supported lead byte is 0xf4 corresponding to U+10FFFF.

  * leadByte might be evaluated multiple times.

  *

  * 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.

  *

  * @param leadByte The first byte of a UTF-8 sequence. Must be 0..0xff.

  * @internal

  */

 #define U8_COUNT_TRAIL_BYTES_UNSAFE(leadByte) \

     (((leadByte)>=0xc0)+((leadByte)>=0xe0)+((leadByte)>=0xf0))

 /**

  * 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.

  *

  * The length can be negative for a NUL-terminated string.

  *

  * 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 int32_t starting string offset

  * @param i int32_t string offset, must be start<=i<length

  * @param length int32_t 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=(i); \

     U8_SET_CP_START(s, start, _u8_get_index); \

     U8_NEXT(s, _u8_get_index, length, c); \

 }

 #ifndef U_HIDE_DRAFT_API

 /**

  * 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 length can be negative for a NUL-terminated string.

  *

  * If the offset points to an illegal UTF-8 byte sequence, then

  * c is set to U+FFFD.

  * Iteration through a string is more efficient with U8_NEXT_UNSAFE or U8_NEXT_OR_FFFD.

  *

  * This macro does not distinguish between a real U+FFFD in the text

  * and U+FFFD returned for an ill-formed sequence.

  * Use U8_GET() if that distinction is important.

  *

  * @param s const uint8_t * string

  * @param start int32_t starting string offset

  * @param i int32_t string offset, must be start<=i<length

  * @param length int32_t string length

  * @param c output UChar32 variable, set to U+FFFD in case of an error

  * @see U8_GET

  * @draft ICU 51

  */

 #define U8_GET_OR_FFFD(s, start, i, length, c) { \

     int32_t _u8_get_index=(i); \

     U8_SET_CP_START(s, start, _u8_get_index); \

     U8_NEXT_OR_FFFD(s, _u8_get_index, length, c); \

 }

 #endif /* U_HIDE_DRAFT_API */

 /* 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((c)>=0x80) { \

         if((c)<0xe0) { \

             (c)=(((c)&0x1f)<<6)|((s)[(i)++]&0x3f); \

         } else if((c)<0xf0) { \

             /* no need for (c&0xf) because the upper bits are truncated after <<12 in the cast to (UChar) */ \

             (c)=(UChar)(((c)<<12)|(((s)[i]&0x3f)<<6)|((s)[(i)+1]&0x3f)); \

             (i)+=2; \

         } else { \

             (c)=(((c)&7)<<18)|(((s)[i]&0x3f)<<12)|(((s)[(i)+1]&0x3f)<<6)|((s)[(i)+2]&0x3f); \

             (i)+=3; \

         } \

     } \

 }

 /**

  * 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 length can be negative for a NUL-terminated string.

  *

  * 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 int32_t string offset, must be i<length

  * @param length int32_t 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) || (length)<0) && \

             (__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)=(((c)&0x1f)<<6)|__t1; \

             ++(i); \

         } else { \

             /* function call for "complicated" and error cases */ \

             (c)=utf8_nextCharSafeBody((const uint8_t *)s, &(i), (length), c, -1); \

         } \

     } \

 }

 #ifndef U_HIDE_DRAFT_API

 /**

  * 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 length can be negative for a NUL-terminated string.

  *

  * 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 U+FFFD.

  *

  * This macro does not distinguish between a real U+FFFD in the text

  * and U+FFFD returned for an ill-formed sequence.

  * Use U8_NEXT() if that distinction is important.

  *

  * @param s const uint8_t * string

  * @param i int32_t string offset, must be i<length

  * @param length int32_t string length

  * @param c output UChar32 variable, set to U+FFFD in case of an error

  * @see U8_NEXT

  * @draft ICU 51

  */

 #define U8_NEXT_OR_FFFD(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) || (length)<0) && \

             (__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)=(((c)&0x1f)<<6)|__t1; \

             ++(i); \

         } else { \

             /* function call for "complicated" and error cases */ \

             (c)=utf8_nextCharSafeBody((const uint8_t *)s, &(i), (length), c, -3); \

         } \

     } \

 }

 #endif /* U_HIDE_DRAFT_API */

 /**

  * 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 int32_t string offset, must be i<capacity

  * @param capacity int32_t size of the string buffer

  * @param c UChar32 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, (i), (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_UNSAFE((uint8_t)(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.

  *

  * The length can be negative for a NUL-terminated string.

  *

  * @param s const uint8_t * string

  * @param i int32_t string offset, must be i<length

  * @param length int32_t 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) && (length)>=0) { \

             __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.

  *

  * The length can be negative for a NUL-terminated string.

  *

  * @param s const uint8_t * string

  * @param i int32_t string offset, must be i<length

  * @param length int32_t 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) || ((length)<0 && (s)[i]!=0))) { \

         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 int32_t starting string offset (usually 0)

  * @param i int32_t 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, (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 int32_t starting string offset (usually 0)

  * @param i int32_t 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) { \

         (c)=utf8_prevCharSafeBody((const uint8_t *)s, start, &(i), c, -1); \

     } \

 }

 #ifndef U_HIDE_DRAFT_API

 /**

  * 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 U+FFFD.

  *

  * This macro does not distinguish between a real U+FFFD in the text

  * and U+FFFD returned for an ill-formed sequence.

  * Use U8_PREV() if that distinction is important.

  *

  * @param s const uint8_t * string

  * @param start int32_t starting string offset (usually 0)

  * @param i int32_t string offset, must be start<i

  * @param c output UChar32 variable, set to U+FFFD in case of an error

  * @see U8_PREV

  * @draft ICU 51

  */

 #define U8_PREV_OR_FFFD(s, start, i, c) { \

     (c)=(uint8_t)(s)[--(i)]; \

     if((c)>=0x80) { \

         (c)=utf8_prevCharSafeBody((const uint8_t *)s, start, &(i), c, -3); \

     } \

 }

 #endif /* U_HIDE_DRAFT_API */

 /**

  * 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 int32_t starting string offset (usually 0)

  * @param i int32_t 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, (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 int32_t index of the start of the string

  * @param i int32_t 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.

  *

  * The length can be negative for a NUL-terminated string.

  *

  * @param s const uint8_t * string

  * @param start int32_t starting string offset (usually 0)

  * @param i int32_t string offset, must be start<=i<=length

  * @param length int32_t 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) || ((length)<0 && (s)[i]!=0))) { \

         U8_BACK_1(s, start, i); \

         U8_FWD_1(s, i, length); \

     } \

 }

 #endif