Check in the pristine copy of ICU 51.2

icu51/source/common/utf_impl.c

Index: icu51/source/common/utf_impl.c
===================================================================
--- icu51/source/common/utf_impl.c	(revision 0)
+++ icu51/source/common/utf_impl.c	(revision 0)
@@ -0,0 +1,326 @@
+/*
+******************************************************************************
+*
+*   Copyright (C) 1999-2012, 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.
+*/
+
+/* set import/export definitions */
+#ifndef U_UTF8_IMPL
+#   define U_UTF8_IMPL
+#endif
+
+#include "unicode/utypes.h"
+#include "unicode/utf.h"
+#include "unicode/utf8.h"
+#include "unicode/utf_old.h"
+#include "uassert.h"
+
+/*
+ * 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.
+ */
+U_EXPORT const uint8_t 
+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]={
+    UTF8_ERROR_VALUE_1, UTF8_ERROR_VALUE_2, UTF_ERROR_VALUE, 0x10ffff,
+    0x3ffffff, 0x7fffffff
+};
+
+static UChar32
+errorValue(int32_t count, int8_t strict) {
+    if(strict>=0) {
+        return utf8_errorValue[count];
+    } else if(strict==-3) {
+        return 0xfffd;
+    } else {
+        return U_SENTINEL;
+    }
+}
+
+/*
+ * Handle the non-inline part of the U8_NEXT() and U8_NEXT_FFFD() macros
+ * and their obsolete sibling UTF8_NEXT_CHAR_SAFE().
+ *
+ * U8_NEXT() supports NUL-terminated strings indicated via length<0.
+ *
+ * The "strict" parameter controls the error behavior:
+ * <0  "Safe" behavior of U8_NEXT():
+ *     -1: All illegal byte sequences yield U_SENTINEL=-1.
+ *     -2: Same as -1, except 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.
+ *     -3: All illegal byte sequences yield U+FFFD.
+ *  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.
+ *
+ * Note that a UBool is the same as an int8_t.
+ */
+U_CAPI UChar32 U_EXPORT2
+utf8_nextCharSafeBody(const uint8_t *s, int32_t *pi, int32_t length, UChar32 c, UBool strict) {
+    int32_t i=*pi;
+    uint8_t count=U8_COUNT_TRAIL_BYTES(c);
+    U_ASSERT(count <= 5); /* U8_COUNT_TRAIL_BYTES returns value 0...5 */
+    if(i+count<=length || length<0) {
+        uint8_t trail;
+
+        U8_MASK_LEAD_BYTE(c, count);
+        /* support NUL-terminated strings: do not read beyond the first non-trail byte */
+        switch(count) {
+        /* each branch falls through to the next one */
+        case 0:
+            /* count==0 for illegally leading trail bytes and the illegal bytes 0xfe and 0xff */
+        case 5:
+        case 4:
+            /* count>=4 is always illegal: no more than 3 trail bytes in Unicode's UTF-8 */
+            break;
+        case 3:
+            trail=s[i++]-0x80;
+            c=(c<<6)|trail;
+            /* c>=0x110 would result in code point>0x10ffff, outside Unicode */
+            if(c>=0x110 || trail>0x3f) { break; }
+        case 2:
+            trail=s[i++]-0x80;
+            c=(c<<6)|trail;
+            /*
+             * test for a surrogate d800..dfff unless we are lenient:
+             * before the last (c<<6), a surrogate is c=360..37f
+             */
+            if(((c&0xffe0)==0x360 && strict!=-2) || trail>0x3f) { break; }
+        case 1:
+            trail=s[i++]-0x80;
+            c=(c<<6)|trail;
+            if(trail>0x3f) { break; }
+            /* correct sequence - all trail bytes have (b7..b6)==(10) */
+            if(c>=utf8_minLegal[count] &&
+                    /* strict: forbid non-characters like U+fffe */
+                    (strict<=0 || !U_IS_UNICODE_NONCHAR(c))) {
+                *pi=i;
+                return c;
+            }
+        /* no default branch to optimize switch()  - all values are covered */
+        }
+    } else {
+        /* too few bytes left */
+        count=length-i;
+    }
+
+    /* error handling */
+    i=*pi;
+    while(count>0 && U8_IS_TRAIL(s[i])) {
+        ++i;
+        --count;
+    }
+    c=errorValue(i-*pi, strict);
+    *pi=i;
+    return c;
+}
+
+U_CAPI int32_t U_EXPORT2
+utf8_appendCharSafeBody(uint8_t *s, int32_t i, int32_t length, UChar32 c, UBool *pIsError) {
+    if((uint32_t)(c)<=0x7ff) {
+        if((i)+1<(length)) {
+            (s)[(i)++]=(uint8_t)(((c)>>6)|0xc0);
+            (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80);
+            return i;
+        }
+    } else if((uint32_t)(c)<=0xffff) {
+        /* Starting with Unicode 3.2, surrogate code points must not be encoded in UTF-8. */
+        if((i)+2<(length) && !U_IS_SURROGATE(c)) {
+            (s)[(i)++]=(uint8_t)(((c)>>12)|0xe0);
+            (s)[(i)++]=(uint8_t)((((c)>>6)&0x3f)|0x80);
+            (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80);
+            return i;
+        }
+    } else if((uint32_t)(c)<=0x10ffff) {
+        if((i)+3<(length)) {
+            (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);
+            return i;
+        }
+    }
+    /* c>0x10ffff or not enough space, write an error value */
+    if(pIsError!=NULL) {
+        *pIsError=TRUE;
+    } else {
+        length-=i;
+        if(length>0) {
+            int32_t offset;
+            if(length>3) {
+                length=3;
+            }
+            s+=i;
+            offset=0;
+            c=utf8_errorValue[length-1];
+            UTF8_APPEND_CHAR_UNSAFE(s, offset, c);
+            i=i+offset;
+        }
+    }
+    return i;
+}
+
+U_CAPI UChar32 U_EXPORT2
+utf8_prevCharSafeBody(const uint8_t *s, int32_t start, int32_t *pi, UChar32 c, UBool strict) {
+    int32_t i=*pi;
+    uint8_t b, count=1, shift=6;
+
+    if(!U8_IS_TRAIL(c)) { return errorValue(0, strict); }
+
+    /* extract value bits from the last trail byte */
+    c&=0x3f;
+
+    for(;;) {
+        if(i<=start) {
+            /* no lead byte at all */
+            return errorValue(0, strict);
+        }
+
+        /* read another previous byte */
+        b=s[--i];
+        if((uint8_t)(b-0x80)<0x7e) { /* 0x80<=b<0xfe */
+            if(b&0x40) {
+                /* lead byte, this will always end the loop */
+                uint8_t shouldCount=U8_COUNT_TRAIL_BYTES(b);
+
+                if(count==shouldCount) {
+                    /* set the new position */
+                    *pi=i;
+                    U8_MASK_LEAD_BYTE(b, count);
+                    c|=(UChar32)b<<shift;
+                    if(count>=4 || c>0x10ffff || c<utf8_minLegal[count] || (U_IS_SURROGATE(c) && strict!=-2) || (strict>0 && U_IS_UNICODE_NONCHAR(c))) {
+                        /* illegal sequence or (strict and non-character) */
+                        if(count>=4) {
+                            count=3;
+                        }
+                        c=errorValue(count, strict);
+                    } else {
+                        /* exit with correct c */
+                    }
+                } else {
+                    /* the lead byte does not match the number of trail bytes */
+                    /* only set the position to the lead byte if it would
+                       include the trail byte that we started with */
+                    if(count<shouldCount) {
+                        *pi=i;
+                        c=errorValue(count, strict);
+                    } else {
+                        c=errorValue(0, strict);
+                    }
+                }
+                break;
+            } else if(count<5) {
+                /* trail byte */
+                c|=(UChar32)(b&0x3f)<<shift;
+                ++count;
+                shift+=6;
+            } else {
+                /* more than 5 trail bytes is illegal */
+                c=errorValue(0, strict);
+                break;
+            }
+        } else {
+            /* single-byte character precedes trailing bytes */
+            c=errorValue(0, strict);
+            break;
+        }
+    }
+    return c;
+}
+
+U_CAPI int32_t U_EXPORT2
+utf8_back1SafeBody(const uint8_t *s, int32_t start, int32_t i) {
+    /* i had been decremented once before the function call */
+    int32_t I=i, Z;
+    uint8_t b;
+
+    /* read at most the 6 bytes s[Z] to s[i], inclusively */
+    if(I-5>start) {
+        Z=I-5;
+    } else {
+        Z=start;
+    }
+
+    /* return I if the sequence starting there is long enough to include i */
+    do {
+        b=s[I];
+        if((uint8_t)(b-0x80)>=0x7e) { /* not 0x80<=b<0xfe */
+            break;
+        } else if(b>=0xc0) {
+            if(U8_COUNT_TRAIL_BYTES(b)>=(i-I)) {
+                return I;
+            } else {
+                break;
+            }
+        }
+    } while(Z<=--I);
+
+    /* return i itself to be consistent with the FWD_1 macro */
+    return i;
+}
Property changes on: icu51/source/common/utf_impl.c
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Added: svn:eol-style
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