408 lines
12 KiB
C
408 lines
12 KiB
C
/*
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*******************************************************************************
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*
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* Copyright (C) 2000, International Business Machines
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* Corporation and others. All Rights Reserved.
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*
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*******************************************************************************
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*
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* File writejava.c
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*
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* Modification History:
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*
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* Date Name Description
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* 01/11/02 Ram Creation.
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*******************************************************************************
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*/
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#include "rle.h"
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/**
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* The ESCAPE character is used during run-length encoding. It signals
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* a run of identical chars.
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*/
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static const uint16_t ESCAPE = 0xA5A5;
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/**
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* The ESCAPE_BYTE character is used during run-length encoding. It signals
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* a run of identical bytes.
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*/
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static const uint8_t ESCAPE_BYTE = (uint8_t)0xA5;
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/**
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* Append a byte to the given StringBuffer, packing two bytes into each
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* character. The state parameter maintains intermediary data between
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* calls.
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* @param state A two-element array, with state[0] == 0 if this is the
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* first byte of a pair, or state[0] != 0 if this is the second byte
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* of a pair, in which case state[1] is the first byte.
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*/
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static uint16_t*
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appendEncodedByte(uint16_t* buffer, uint16_t* buffLimit, uint8_t value, uint8_t state[],UErrorCode* status) {
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if(!status || U_FAILURE(*status)){
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return NULL;
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}
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if (state[0] != 0) {
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uint16_t c = (uint16_t) ((state[1] << 8) | (((int32_t) value) & 0xFF));
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if(buffer < buffLimit){
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*buffer++ = c;
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}else{
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*status = U_BUFFER_OVERFLOW_ERROR;
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}
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state[0] = 0;
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return buffer;
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}
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else {
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state[0] = 1;
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state[1] = value;
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return buffer;
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}
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}
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/**
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* Encode a run, possibly a degenerate run (of < 4 values).
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* @param length The length of the run; must be > 0 && <= 0xFF.
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*/
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static uint16_t*
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encodeRunByte(uint16_t* buffer,uint16_t* bufLimit, uint8_t value, int32_t length, uint8_t state[], UErrorCode* status) {
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if(!status || U_FAILURE(*status)){
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return NULL;
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}
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if (length < 4) {
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int32_t j=0;
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for (; j<length; ++j) {
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if (value == ESCAPE_BYTE) {
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buffer = appendEncodedByte(buffer,bufLimit, ESCAPE_BYTE, state,status);
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}
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buffer = appendEncodedByte(buffer,bufLimit, value, state, status);
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}
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}
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else {
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if (length == ESCAPE_BYTE) {
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if (value == ESCAPE_BYTE){
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buffer = appendEncodedByte(buffer, bufLimit,ESCAPE_BYTE, state,status);
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}
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buffer = appendEncodedByte(buffer,bufLimit, value, state, status);
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--length;
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}
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buffer = appendEncodedByte(buffer,bufLimit, ESCAPE_BYTE, state,status);
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buffer = appendEncodedByte(buffer,bufLimit, (char)length, state, status);
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buffer = appendEncodedByte(buffer,bufLimit, value, state, status); /* Don't need to escape this value*/
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}
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return buffer;
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}
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#define APPEND( buffer, bufLimit, value, status){ \
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if(buffer<bufLimit){ \
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*buffer++=(value); \
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}else{ \
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*status = U_BUFFER_OVERFLOW_ERROR; \
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return (uint16_t*)(buffer - saveBuf); \
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} \
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}
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/**
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* Encode a run, possibly a degenerate run (of < 4 values).
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* @param length The length of the run; must be > 0 && <= 0xFFFF.
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*/
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static uint16_t*
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encodeRunShort(uint16_t* buffer,uint16_t* bufLimit, uint16_t value, int32_t length,UErrorCode* status) {
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uint16_t* saveBuf = buffer;
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if (length < 4) {
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int j=0;
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for (; j<length; ++j) {
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if (value == (int32_t) ESCAPE){
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APPEND(buffer,bufLimit,ESCAPE,status);
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}
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APPEND(buffer,bufLimit,value,status);
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}
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}
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else {
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if (length == (int32_t) ESCAPE) {
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if (value == (int32_t) ESCAPE){
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APPEND(buffer,bufLimit,ESCAPE,status);
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}
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APPEND(buffer,bufLimit,value,status);
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--length;
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}
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APPEND(buffer,bufLimit,ESCAPE,status);
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APPEND(buffer,bufLimit,(uint16_t) length,status);
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APPEND(buffer,bufLimit,(uint16_t)value,status); /* Don't need to escape this value */
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}
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return buffer;
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}
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/**
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* Construct a string representing a char array. Use run-length encoding.
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* A character represents itself, unless it is the ESCAPE character. Then
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* the following notations are possible:
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* ESCAPE ESCAPE ESCAPE literal
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* ESCAPE n c n instances of character c
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* Since an encoded run occupies 3 characters, we only encode runs of 4 or
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* more characters. Thus we have n > 0 and n != ESCAPE and n <= 0xFFFF.
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* If we encounter a run where n == ESCAPE, we represent this as:
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* c ESCAPE n-1 c
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* The ESCAPE value is chosen so as not to collide with commonly
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* seen values.
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*/
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int32_t
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usArrayToRLEString(const uint16_t* src,int32_t srcLen,uint16_t* buffer, int32_t bufLen,UErrorCode* status) {
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const uint16_t* saveBuf = buffer;
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uint16_t* bufLimit = buffer+bufLen;
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if(buffer < bufLimit){
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*buffer++ = (uint16_t)(srcLen>>16);
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if(buffer<bufLimit){
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uint16_t runValue = src[0];
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int32_t runLength = 1;
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int i=1;
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*buffer++ = (uint16_t) srcLen;
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for (; i<srcLen; ++i) {
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uint16_t s = src[i];
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if (s == runValue && runLength < 0xFFFF){
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++runLength;
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}else {
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buffer = encodeRunShort(buffer,bufLimit, (uint16_t)runValue, runLength,status);
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if(U_FAILURE(*status)){
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return (int32_t) (buffer - saveBuf);
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}
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runValue = s;
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runLength = 1;
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}
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}
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buffer = encodeRunShort(buffer,bufLimit,(uint16_t)runValue, runLength,status);
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}else{
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*status = U_BUFFER_OVERFLOW_ERROR;
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}
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}else{
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*status = U_BUFFER_OVERFLOW_ERROR;
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}
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return (int32_t) (buffer - saveBuf);
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}
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/**
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* Construct a string representing a byte array. Use run-length encoding.
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* Two bytes are packed into a single char, with a single extra zero byte at
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* the end if needed. A byte represents itself, unless it is the
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* ESCAPE_BYTE. Then the following notations are possible:
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* ESCAPE_BYTE ESCAPE_BYTE ESCAPE_BYTE literal
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* ESCAPE_BYTE n b n instances of byte b
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* Since an encoded run occupies 3 bytes, we only encode runs of 4 or
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* more bytes. Thus we have n > 0 and n != ESCAPE_BYTE and n <= 0xFF.
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* If we encounter a run where n == ESCAPE_BYTE, we represent this as:
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* b ESCAPE_BYTE n-1 b
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* The ESCAPE_BYTE value is chosen so as not to collide with commonly
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* seen values.
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*/
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int32_t
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byteArrayToRLEString(const uint8_t* src,int32_t srcLen, uint16_t* buffer,int32_t bufLen, UErrorCode* status) {
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const uint16_t* saveBuf = buffer;
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uint16_t* bufLimit = buffer+bufLen;
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if(buffer < bufLimit){
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*buffer++ = ((uint16_t) (srcLen >> 16));
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if(buffer<bufLimit){
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uint8_t runValue = src[0];
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int runLength = 1;
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uint8_t state[2]= {0};
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int i=1;
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*buffer++=((uint16_t) srcLen);
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for (; i<srcLen; ++i) {
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uint8_t b = src[i];
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if (b == runValue && runLength < 0xFF){
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++runLength;
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}
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else {
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buffer = encodeRunByte(buffer, bufLimit,runValue, runLength, state,status);
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runValue = b;
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runLength = 1;
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}
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}
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buffer = encodeRunByte(buffer,bufLimit, runValue, runLength, state, status);
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/* We must save the final byte, if there is one, by padding
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* an extra zero.
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*/
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if (state[0] != 0) {
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buffer = appendEncodedByte(buffer,bufLimit, 0, state ,status);
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}
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}else{
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*status = U_BUFFER_OVERFLOW_ERROR;
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}
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}else{
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*status = U_BUFFER_OVERFLOW_ERROR;
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}
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return (int32_t) (buffer - saveBuf);
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}
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/**
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* Construct an array of shorts from a run-length encoded string.
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*/
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int32_t
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rleStringToUCharArray(uint16_t* src, int32_t srcLen, uint16_t* target, int32_t tgtLen, UErrorCode* status) {
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int32_t length = 0;
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int32_t ai = 0;
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int i=2;
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if(!status || U_FAILURE(*status)){
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return 0;
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}
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/* the source is null terminated */
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if(srcLen == -1){
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srcLen = u_strlen(src);
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}
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if(srcLen <= 2){
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return 2;
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}
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length = (((int32_t) src[0]) << 16) | ((int32_t) src[1]);
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if(target == NULL){
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return length;
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}
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if(tgtLen < length){
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*status = U_BUFFER_OVERFLOW_ERROR;
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return length;
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}
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for (; i<srcLen; ++i) {
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uint16_t c = src[i];
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if (c == ESCAPE) {
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c = src[++i];
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if (c == ESCAPE) {
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target[ai++] = c;
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} else {
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int32_t runLength = (int32_t) c;
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uint16_t runValue = src[++i];
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int j=0;
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for (; j<runLength; ++j) {
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target[ai++] = runValue;
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}
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}
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}
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else {
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target[ai++] = c;
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}
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}
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if (ai != length){
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*status = U_INTERNAL_PROGRAM_ERROR;
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}
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return length;
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}
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/**
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* Construct an array of bytes from a run-length encoded string.
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*/
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int32_t
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rleStringToByteArray(uint16_t* src, int32_t srcLen, uint8_t* target, int32_t tgtLen, UErrorCode* status) {
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int32_t length = 0;
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UBool nextChar = TRUE;
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uint16_t c = 0;
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int32_t node = 0;
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int32_t runLength = 0;
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int32_t i = 2;
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int32_t ai=0;
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if(!status || U_FAILURE(*status)){
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return 0;
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}
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/* the source is null terminated */
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if(srcLen == -1){
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srcLen = u_strlen(src);
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}
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if(srcLen <= 2){
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return 2;
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}
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length = (((int32_t) src[0]) << 16) | ((int32_t) src[1]);
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if(target == NULL){
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return length;
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}
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if(tgtLen < length){
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*status = U_BUFFER_OVERFLOW_ERROR;
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return length;
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}
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for (; ai<tgtLen; ) {
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/* This part of the loop places the next byte into the local
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* variable 'b' each time through the loop. It keeps the
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* current character in 'c' and uses the boolean 'nextChar'
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* to see if we've taken both bytes out of 'c' yet.
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*/
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uint8_t b;
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if (nextChar) {
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c = src[i++];
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b = (uint8_t) (c >> 8);
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nextChar = FALSE;
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}
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else {
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b = (uint8_t) (c & 0xFF);
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nextChar = TRUE;
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}
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/* This part of the loop is a tiny state machine which handles
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* the parsing of the run-length encoding. This would be simpler
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* if we could look ahead, but we can't, so we use 'node' to
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* move between three nodes in the state machine.
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*/
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switch (node) {
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case 0:
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/* Normal idle node */
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if (b == ESCAPE_BYTE) {
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node = 1;
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}
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else {
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target[ai++] = b;
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}
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break;
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case 1:
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/* We have seen one ESCAPE_BYTE; we expect either a second
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* one, or a run length and value.
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*/
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if (b == ESCAPE_BYTE) {
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target[ai++] = ESCAPE_BYTE;
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node = 0;
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}
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else {
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runLength = b;
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node = 2;
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}
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break;
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case 2:
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{
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int j=0;
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/* We have seen an ESCAPE_BYTE and length byte. We interpret
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* the next byte as the value to be repeated.
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*/
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for (; j<runLength; ++j){
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if(ai<tgtLen){
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target[ai++] = b;
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}else{
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*status = U_BUFFER_OVERFLOW_ERROR;
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return ai;
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}
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}
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node = 0;
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break;
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}
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}
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}
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if (node != 0){
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*status = U_INTERNAL_PROGRAM_ERROR;
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/*("Bad run-length encoded byte array")*/
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return 0;
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}
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if (i != srcLen){
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/*("Excess data in RLE byte array string");*/
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*status = U_INTERNAL_PROGRAM_ERROR;
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return ai;
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}
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return ai;
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}
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