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Add Apple ADC algorithm.

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Natalia Portillo
2021-10-17 04:45:11 +01:00
parent 722175d2ae
commit b12b12f8f4
6 changed files with 226 additions and 2 deletions
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125
adc.c Normal file
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//
// Created by claunia on 17/10/21.
//
#include <stdint.h>
#include <string.h>
#include "library.h"
#include "adc.h"
FORCE_INLINE int GetChunkType(uint8_t byt)
{
if(byt & 0x80) return ADC_PLAIN;
if(byt & 0x40) return ADC_THREE_BYTE;
return ADC_TWO_BYTE;
}
FORCE_INLINE int GetChunkSize(uint8_t byt)
{
switch(GetChunkType(byt))
{
case ADC_PLAIN: return (byt & 0x7F) + 1;
case ADC_TWO_BYTE: return ((byt & 0x3F) >> 2) + 3;
case ADC_THREE_BYTE: return (byt & 0x3F) + 4;
default: return -1;
}
}
FORCE_INLINE int GetOffset(uint8_t chunk[])
{
switch(GetChunkType(chunk[0]))
{
case ADC_PLAIN: return 0;
case ADC_TWO_BYTE: return ((chunk[0] & 0x03) << 8) + chunk[1];
case ADC_THREE_BYTE: return (chunk[1] << 8) + chunk[2];
default: return -1;
}
}
AARU_EXPORT int32_t AARU_CALL adc_decode_buffer(uint8_t* dst_buffer,
int32_t dst_size,
const uint8_t* src_buffer,
int32_t src_size)
{
int inputPosition = 0;
int chunkSize;
int offset;
int chunkType;
int outPosition = 0;
uint8_t temp[3];
uint8_t readByte;
uint8_t lastByte;
int i;
while(inputPosition < src_size)
{
readByte = src_buffer[inputPosition++];
chunkType = GetChunkType(readByte);
switch(chunkType)
{
case ADC_PLAIN:
chunkSize = GetChunkSize(readByte);
if(outPosition + chunkSize > dst_size) goto finished;
memcpy(dst_buffer + outPosition, src_buffer + inputPosition, chunkSize);
outPosition += chunkSize;
inputPosition += chunkSize;
break;
case ADC_TWO_BYTE:
chunkSize = GetChunkSize(readByte);
temp[0] = readByte;
temp[1] = src_buffer[inputPosition++];
offset = GetOffset(temp);
if(outPosition + chunkSize > dst_size) goto finished;
if(offset == 0)
{
lastByte = dst_buffer[outPosition - 1];
for(i = 0; i < chunkSize; i++)
{
dst_buffer[outPosition] = lastByte;
outPosition++;
}
}
else
{
for(i = 0; i < chunkSize; i++)
{
dst_buffer[outPosition] = dst_buffer[outPosition - offset - 1];
outPosition++;
}
}
break;
case ADC_THREE_BYTE:
chunkSize = GetChunkSize(readByte);
temp[0] = readByte;
temp[1] = src_buffer[inputPosition++];
temp[2] = src_buffer[inputPosition++];
offset = GetOffset(temp);
if(outPosition + chunkSize > dst_size) goto finished;
if(offset == 0)
{
lastByte = dst_buffer[outPosition - 1];
for(i = 0; i < chunkSize; i++)
{
dst_buffer[outPosition] = lastByte;
outPosition++;
}
}
else
{
for(i = 0; i < chunkSize; i++)
{
dst_buffer[outPosition] = dst_buffer[outPosition - offset - 1];
outPosition++;
}
}
break;
}
}
finished:
return outPosition;
}