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+/*
+******************************************************************************
+*
+* Copyright (C) 1999-2006, International Business Machines
+* Corporation and others. All Rights Reserved.
+*
+******************************************************************************
+* file name: utf_impl.c
+* encoding: US-ASCII
+* tab size: 8 (not used)
+* indentation:4
+*
+* created on: 1999sep13
+* created by: Markus W. Scherer
+*
+* This file provides implementation functions for macros in the utfXX.h
+* that would otherwise be too long as macros.
+*/
+
+#include "base/third_party/icu/icu_utf.h"
+
+namespace base_icu {
+
+/**
+ * UTF8_ERROR_VALUE_1 and UTF8_ERROR_VALUE_2 are special error values for UTF-8,
+ * which need 1 or 2 bytes in UTF-8:
+ * \code
+ * U+0015 = NAK = Negative Acknowledge, C0 control character
+ * U+009f = highest C1 control character
+ * \endcode
+ *
+ * These are used by UTF8_..._SAFE macros so that they can return an error value
+ * that needs the same number of code units (bytes) as were seen by
+ * a macro. They should be tested with UTF_IS_ERROR() or UTF_IS_VALID().
+ *
+ * @deprecated ICU 2.4. Obsolete, see utf_old.h.
+ */
+#define CBUTF8_ERROR_VALUE_1 0x15
+
+/**
+ * See documentation on UTF8_ERROR_VALUE_1 for details.
+ *
+ * @deprecated ICU 2.4. Obsolete, see utf_old.h.
+ */
+#define CBUTF8_ERROR_VALUE_2 0x9f
+
+
+/**
+ * Error value for all UTFs. This code point value will be set by macros with e>
+ * checking if an error is detected.
+ *
+ * @deprecated ICU 2.4. Obsolete, see utf_old.h.
+ */
+#define CBUTF_ERROR_VALUE 0xffff
+
+/*
+ * This table could be replaced on many machines by
+ * a few lines of assembler code using an
+ * "index of first 0-bit from msb" instruction and
+ * one or two more integer instructions.
+ *
+ * For example, on an i386, do something like
+ * - MOV AL, leadByte
+ * - NOT AL (8-bit, leave b15..b8==0..0, reverse only b7..b0)
+ * - MOV AH, 0
+ * - BSR BX, AX (16-bit)
+ * - MOV AX, 6 (result)
+ * - JZ finish (ZF==1 if leadByte==0xff)
+ * - SUB AX, BX (result)
+ * -finish:
+ * (BSR: Bit Scan Reverse, scans for a 1-bit, starting from the MSB)
+ *
+ * In Unicode, all UTF-8 byte sequences with more than 4 bytes are illegal;
+ * lead bytes above 0xf4 are illegal.
+ * We keep them in this table for skipping long ISO 10646-UTF-8 sequences.
+ */
+const uint8
+utf8_countTrailBytes[256]={
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+
+ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+
+ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+ 3, 3, 3, 3, 3,
+ 3, 3, 3, /* illegal in Unicode */
+ 4, 4, 4, 4, /* illegal in Unicode */
+ 5, 5, /* illegal in Unicode */
+ 0, 0 /* illegal bytes 0xfe and 0xff */
+};
+
+static const UChar32
+utf8_minLegal[4]={ 0, 0x80, 0x800, 0x10000 };
+
+static const UChar32
+utf8_errorValue[6]={
+ CBUTF8_ERROR_VALUE_1, CBUTF8_ERROR_VALUE_2, CBUTF_ERROR_VALUE, 0x10ffff,
+ 0x3ffffff, 0x7fffffff
+};
+
+/*
+ * Handle the non-inline part of the U8_NEXT() macro and its obsolete sibling
+ * UTF8_NEXT_CHAR_SAFE().
+ *
+ * The "strict" parameter controls the error behavior:
+ * <0 "Safe" behavior of U8_NEXT(): All illegal byte sequences yield a negative
+ * code point result.
+ * 0 Obsolete "safe" behavior of UTF8_NEXT_CHAR_SAFE(..., FALSE):
+ * All illegal byte sequences yield a positive code point such that this
+ * result code point would be encoded with the same number of bytes as
+ * the illegal sequence.
+ * >0 Obsolete "strict" behavior of UTF8_NEXT_CHAR_SAFE(..., TRUE):
+ * Same as the obsolete "safe" behavior, but non-characters are also treated
+ * like illegal sequences.
+ *
+ * The special negative (<0) value -2 is used for lenient treatment of surrogate
+ * code points as legal. Some implementations use this for roundtripping of
+ * Unicode 16-bit strings that are not well-formed UTF-16, that is, they
+ * contain unpaired surrogates.
+ *
+ * Note that a UBool is the same as an int8_t.
+ */
+UChar32
+utf8_nextCharSafeBody(const uint8 *s, int32 *pi, int32 length, UChar32 c, UBool strict) {
+ int32 i=*pi;
+ uint8 count=CBU8_COUNT_TRAIL_BYTES(c);
+ if((i)+count<=(length)) {
+ uint8 trail, illegal=0;
+
+ CBU8_MASK_LEAD_BYTE((c), count);
+ /* count==0 for illegally leading trail bytes and the illegal bytes 0xfe and 0xff */
+ switch(count) {
+ /* each branch falls through to the next one */
+ case 5:
+ case 4:
+ /* count>=4 is always illegal: no more than 3 trail bytes in Unicode's UTF-8 */
+ illegal=1;
+ break;
+ case 3:
+ trail=s[(i)++];
+ (c)=((c)<<6)|(trail&0x3f);
+ if(c<0x110) {
+ illegal|=(trail&0xc0)^0x80;
+ } else {
+ /* code point>0x10ffff, outside Unicode */
+ illegal=1;
+ break;
+ }
+ case 2:
+ trail=s[(i)++];
+ (c)=((c)<<6)|(trail&0x3f);
+ illegal|=(trail&0xc0)^0x80;
+ case 1:
+ trail=s[(i)++];
+ (c)=((c)<<6)|(trail&0x3f);
+ illegal|=(trail&0xc0)^0x80;
+ break;
+ case 0:
+ if(strict>=0) {
+ return CBUTF8_ERROR_VALUE_1;
+ } else {
+ return CBU_SENTINEL;
+ }
+ /* no default branch to optimize switch() - all values are covered */
+ }
+
+ /*
+ * All the error handling should return a value
+ * that needs count bytes so that UTF8_GET_CHAR_SAFE() works right.
+ *
+ * Starting with Unicode 3.0.1, non-shortest forms are illegal.
+ * Starting with Unicode 3.2, surrogate code points must not be
+ * encoded in UTF-8, and there are no irregular sequences any more.
+ *
+ * U8_ macros (new in ICU 2.4) return negative values for error conditions.
+ */
+
+ /* correct sequence - all trail bytes have (b7..b6)==(10)? */
+ /* illegal is also set if count>=4 */
+ if(illegal || (c)<utf8_minLegal[count] || (CBU_IS_SURROGATE(c) && strict!=-2)) {
+ /* error handling */
+ uint8 errorCount=count;
+ /* don't go beyond this sequence */
+ i=*pi;
+ while(count>0 && CBU8_IS_TRAIL(s[i])) {
+ ++(i);
+ --count;
+ }
+ if(strict>=0) {
+ c=utf8_errorValue[errorCount-count];
+ } else {
+ c=CBU_SENTINEL;
+ }
+ } else if((strict)>0 && CBU_IS_UNICODE_NONCHAR(c)) {
+ /* strict: forbid non-characters like U+fffe */
+ c=utf8_errorValue[count];
+ }
+ } else /* too few bytes left */ {
+ /* error handling */
+ int32 i0=i;
+ /* don't just set (i)=(length) in case there is an illegal sequence */
+ while((i)<(length) && CBU8_IS_TRAIL(s[i])) {
+ ++(i);
+ }
+ if(strict>=0) {
+ c=utf8_errorValue[i-i0];
+ } else {
+ c=CBU_SENTINEL;
+ }
+ }
+ *pi=i;
+ return c;
+}
+
+} // namespace base_icu
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