// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
*******************************************************************************
*
* Copyright (C) 2000-2003, International Business Machines
* Corporation and others. All Rights Reserved.
*
*******************************************************************************
*
* File writejava.c
*
* Modification History:
*
* Date Name Description
* 01/11/02 Ram Creation.
*******************************************************************************
*/
#include "rle.h"
/**
* The ESCAPE character is used during run-length encoding. It signals
* a run of identical chars.
*/
static const uint16_t ESCAPE = 0xA5A5;
/**
* The ESCAPE_BYTE character is used during run-length encoding. It signals
* a run of identical bytes.
*/
static const uint8_t ESCAPE_BYTE = (uint8_t)0xA5;
/**
* Append a byte to the given StringBuffer, packing two bytes into each
* character. The state parameter maintains intermediary data between
* calls.
* @param state A two-element array, with state[0] == 0 if this is the
* first byte of a pair, or state[0] != 0 if this is the second byte
* of a pair, in which case state[1] is the first byte.
*/
static uint16_t*
appendEncodedByte(uint16_t* buffer, uint16_t* buffLimit, uint8_t value, uint8_t state[],UErrorCode* status) {
if(!status || U_FAILURE(*status)){
return NULL;
}
if (state[0] != 0) {
uint16_t c = (uint16_t) ((state[1] << 8) | (((int32_t) value) & 0xFF));
if(buffer < buffLimit){
*buffer++ = c;
}else{
*status = U_BUFFER_OVERFLOW_ERROR;
}
state[0] = 0;
return buffer;
}
else {
state[0] = 1;
state[1] = value;
return buffer;
}
}
/**
* Encode a run, possibly a degenerate run (of < 4 values).
* @param length The length of the run; must be > 0 && <= 0xFF.
*/
static uint16_t*
encodeRunByte(uint16_t* buffer,uint16_t* bufLimit, uint8_t value, int32_t length, uint8_t state[], UErrorCode* status) {
if(!status || U_FAILURE(*status)){
return NULL;
}
if (length < 4) {
int32_t j=0;
for (; j<length; ++j) {
if (value == ESCAPE_BYTE) {
buffer = appendEncodedByte(buffer,bufLimit, ESCAPE_BYTE, state,status);
}
buffer = appendEncodedByte(buffer,bufLimit, value, state, status);
}
}
else {
if (length == ESCAPE_BYTE) {
if (value == ESCAPE_BYTE){
buffer = appendEncodedByte(buffer, bufLimit,ESCAPE_BYTE, state,status);
}
buffer = appendEncodedByte(buffer,bufLimit, value, state, status);
--length;
}
buffer = appendEncodedByte(buffer,bufLimit, ESCAPE_BYTE, state,status);
buffer = appendEncodedByte(buffer,bufLimit, (char)length, state, status);
buffer = appendEncodedByte(buffer,bufLimit, value, state, status); /* Don't need to escape this value*/
}
return buffer;
}
#define APPEND( buffer, bufLimit, value, num, status){ \
if(buffer<bufLimit){ \
*buffer++=(value); \
}else{ \
*status = U_BUFFER_OVERFLOW_ERROR; \
} \
num++; \
}
/**
* Encode a run, possibly a degenerate run (of < 4 values).
* @param length The length of the run; must be > 0 && <= 0xFFFF.
*/
static uint16_t*
encodeRunShort(uint16_t* buffer,uint16_t* bufLimit, uint16_t value, int32_t length,UErrorCode* status) {
int32_t num=0;
if (length < 4) {
int j=0;
for (; j<length; ++j) {
if (value == (int32_t) ESCAPE){
APPEND(buffer,bufLimit,ESCAPE, num, status);
}
APPEND(buffer,bufLimit,value,num, status);
}
}
else {
if (length == (int32_t) ESCAPE) {
if (value == (int32_t) ESCAPE){
APPEND(buffer,bufLimit,ESCAPE,num,status);
}
APPEND(buffer,bufLimit,value,num,status);
--length;
}
APPEND(buffer,bufLimit,ESCAPE,num,status);
APPEND(buffer,bufLimit,(uint16_t) length, num,status);
APPEND(buffer,bufLimit,(uint16_t)value, num, status); /* Don't need to escape this value */
}
return buffer;
}
/**
* Construct a string representing a char array. Use run-length encoding.
* A character represents itself, unless it is the ESCAPE character. Then
* the following notations are possible:
* ESCAPE ESCAPE ESCAPE literal
* ESCAPE n c n instances of character c
* Since an encoded run occupies 3 characters, we only encode runs of 4 or
* more characters. Thus we have n > 0 and n != ESCAPE and n <= 0xFFFF.
* If we encounter a run where n == ESCAPE, we represent this as:
* c ESCAPE n-1 c
* The ESCAPE value is chosen so as not to collide with commonly
* seen values.
*/
int32_t
usArrayToRLEString(const uint16_t* src,int32_t srcLen,uint16_t* buffer, int32_t bufLen,UErrorCode* status) {
uint16_t* bufLimit = buffer+bufLen;
uint16_t* saveBuffer = buffer;
if(buffer < bufLimit){
*buffer++ = (uint16_t)(srcLen>>16);
if(buffer<bufLimit){
uint16_t runValue = src[0];
int32_t runLength = 1;
int i=1;
*buffer++ = (uint16_t) srcLen;
for (; i<srcLen; ++i) {
uint16_t s = src[i];
if (s == runValue && runLength < 0xFFFF){
++runLength;
}else {
buffer = encodeRunShort(buffer,bufLimit, (uint16_t)runValue, runLength,status);
runValue = s;
runLength = 1;
}
}
buffer= encodeRunShort(buffer,bufLimit,(uint16_t)runValue, runLength,status);
}else{
*status = U_BUFFER_OVERFLOW_ERROR;
}
}else{
*status = U_BUFFER_OVERFLOW_ERROR;
}
return (int32_t)(buffer - saveBuffer);
}
/**
* Construct a string representing a byte array. Use run-length encoding.
* Two bytes are packed into a single char, with a single extra zero byte at
* the end if needed. A byte represents itself, unless it is the
* ESCAPE_BYTE. Then the following notations are possible:
* ESCAPE_BYTE ESCAPE_BYTE ESCAPE_BYTE literal
* ESCAPE_BYTE n b n instances of byte b
* Since an encoded run occupies 3 bytes, we only encode runs of 4 or
* more bytes. Thus we have n > 0 and n != ESCAPE_BYTE and n <= 0xFF.
* If we encounter a run where n == ESCAPE_BYTE, we represent this as:
* b ESCAPE_BYTE n-1 b
* The ESCAPE_BYTE value is chosen so as not to collide with commonly
* seen values.
*/
int32_t
byteArrayToRLEString(const uint8_t* src,int32_t srcLen, uint16_t* buffer,int32_t bufLen, UErrorCode* status) {
const uint16_t* saveBuf = buffer;
uint16_t* bufLimit = buffer+bufLen;
if(buffer < bufLimit){
*buffer++ = ((uint16_t) (srcLen >> 16));
if(buffer<bufLimit){
uint8_t runValue = src[0];
int runLength = 1;
uint8_t state[2]= {0};
int i=1;
*buffer++=((uint16_t) srcLen);
for (; i<srcLen; ++i) {
uint8_t b = src[i];
if (b == runValue && runLength < 0xFF){
++runLength;
}
else {
buffer = encodeRunByte(buffer, bufLimit,runValue, runLength, state,status);
runValue = b;
runLength = 1;
}
}
buffer = encodeRunByte(buffer,bufLimit, runValue, runLength, state, status);
/* We must save the final byte, if there is one, by padding
* an extra zero.
*/
if (state[0] != 0) {
buffer = appendEncodedByte(buffer,bufLimit, 0, state ,status);
}
}else{
*status = U_BUFFER_OVERFLOW_ERROR;
}
}else{
*status = U_BUFFER_OVERFLOW_ERROR;
}
return (int32_t) (buffer - saveBuf);
}
/**
* Construct an array of shorts from a run-length encoded string.
*/
int32_t
rleStringToUCharArray(uint16_t* src, int32_t srcLen, uint16_t* target, int32_t tgtLen, UErrorCode* status) {
int32_t length = 0;
int32_t ai = 0;
int i=2;
if(!status || U_FAILURE(*status)){
return 0;
}
/* the source is null terminated */
if(srcLen == -1){
srcLen = u_strlen(src);
}
if(srcLen <= 2){
return 2;
}
length = (((int32_t) src[0]) << 16) | ((int32_t) src[1]);
if(target == NULL){
return length;
}
if(tgtLen < length){
*status = U_BUFFER_OVERFLOW_ERROR;
return length;
}
for (; i<srcLen; ++i) {
uint16_t c = src[i];
if (c == ESCAPE) {
c = src[++i];
if (c == ESCAPE) {
target[ai++] = c;
} else {
int32_t runLength = (int32_t) c;
uint16_t runValue = src[++i];
int j=0;
for (; j<runLength; ++j) {
target[ai++] = runValue;
}
}
}
else {
target[ai++] = c;
}
}
if (ai != length){
*status = U_INTERNAL_PROGRAM_ERROR;
}
return length;
}
/**
* Construct an array of bytes from a run-length encoded string.
*/
int32_t
rleStringToByteArray(uint16_t* src, int32_t srcLen, uint8_t* target, int32_t tgtLen, UErrorCode* status) {
int32_t length = 0;
UBool nextChar = TRUE;
uint16_t c = 0;
int32_t node = 0;
int32_t runLength = 0;
int32_t i = 2;
int32_t ai=0;
if(!status || U_FAILURE(*status)){
return 0;
}
/* the source is null terminated */
if(srcLen == -1){
srcLen = u_strlen(src);
}
if(srcLen <= 2){
return 2;
}
length = (((int32_t) src[0]) << 16) | ((int32_t) src[1]);
if(target == NULL){
return length;
}
if(tgtLen < length){
*status = U_BUFFER_OVERFLOW_ERROR;
return length;
}
for (; ai<tgtLen; ) {
/* This part of the loop places the next byte into the local
* variable 'b' each time through the loop. It keeps the
* current character in 'c' and uses the boolean 'nextChar'
* to see if we've taken both bytes out of 'c' yet.
*/
uint8_t b;
if (nextChar) {
c = src[i++];
b = (uint8_t) (c >> 8);
nextChar = FALSE;
}
else {
b = (uint8_t) (c & 0xFF);
nextChar = TRUE;
}
/* This part of the loop is a tiny state machine which handles
* the parsing of the run-length encoding. This would be simpler
* if we could look ahead, but we can't, so we use 'node' to
* move between three nodes in the state machine.
*/
switch (node) {
case 0:
/* Normal idle node */
if (b == ESCAPE_BYTE) {
node = 1;
}
else {
target[ai++] = b;
}
break;
case 1:
/* We have seen one ESCAPE_BYTE; we expect either a second
* one, or a run length and value.
*/
if (b == ESCAPE_BYTE) {
target[ai++] = ESCAPE_BYTE;
node = 0;
}
else {
runLength = b;
node = 2;
}
break;
case 2:
{
int j=0;
/* We have seen an ESCAPE_BYTE and length byte. We interpret
* the next byte as the value to be repeated.
*/
for (; j<runLength; ++j){
if(ai<tgtLen){
target[ai++] = b;
}else{
*status = U_BUFFER_OVERFLOW_ERROR;
return ai;
}
}
node = 0;
break;
}
}
}
if (node != 0){
*status = U_INTERNAL_PROGRAM_ERROR;
/*("Bad run-length encoded byte array")*/
return 0;
}
if (i != srcLen){
/*("Excess data in RLE byte array string");*/
*status = U_INTERNAL_PROGRAM_ERROR;
return ai;
}
return ai;
}