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UAVCAN: change hex2nibble method to use branching instead of plain lookup table

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Siddharth Purohit 2019-01-23 11:17:36 +08:00 committed by Andrew Tridgell
parent 2c0521654c
commit 38125ab92a
1 changed files with 17 additions and 18 deletions
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35
libraries/AP_UAVCAN/AP_UAVCAN_SLCAN.cpp
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@ -44,27 +44,26 @@ static bool hex2nibble_error;
static uint8_t hex2nibble(char ch) static uint8_t hex2nibble(char ch)
{ {
// Must go into RAM, not flash, because flash is slow // Must go into RAM, not flash, because flash is slow
static uint8_t ConversionTable[] = static uint8_t NumConversionTable[] =
{ {
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, // 0..9
255, 255, 255, 255, 255, 255, 255,
10, 11, 12, 13, 14, 15, // A..F
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255,
10, 11, 12, 13, 14, 15, // a..f
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255
}; };
const uint8_t out = ConversionTable[int(ch)]; static uint8_t AlphaConversionTable[] =
{
10, 11, 12, 13, 14, 15
};
uint8_t out = 255;
if (ch >= '0' && ch <= '9') {
out = NumConversionTable[int(ch) - int('0')];
} else if (ch >= 'a' && ch <= 'f') {
out = AlphaConversionTable[int(ch) - int('a')];
} else if (ch >= 'A' && ch <= 'F') {
out = AlphaConversionTable[int(ch) - int('A')];
}
if (out == 255) if (out == 255)
{ {
hex2nibble_error = true; hex2nibble_error = true;