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simplify bitwise operations #4

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simplify bitwise operations #4

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d57eb7c
simplify bitwise operations
HannesGitH Dec 15, 2020
76715cb
forgot two semicoli
HannesGitH Feb 27, 2021
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23 changes: 9 additions & 14 deletions ChainableLED.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -68,14 +68,11 @@ void ChainableLED::clk(void)

void ChainableLED::sendByte(byte b)
{
// Send one bit at a time, starting with the MSB
for (byte i=0; i<8; i++)
// Send one bit at a time, starting with the MSB (bit 7)
for (int i=7; i>=0; i--)
{
// If MSB is 1, write one and clock it, else write 0 and clock
if ((b & 0x80) != 0)
digitalWrite(_data_pin, HIGH);
else
digitalWrite(_data_pin, LOW);
// send i-th bit and clock it
digitalWrite(_data_pin,(b>>i)&1);
clk();

// Advance to the next bit to send
Expand All @@ -86,13 +83,11 @@ void ChainableLED::sendByte(byte b)
void ChainableLED::sendColor(byte red, byte green, byte blue)
{
// Start by sending a byte with the format "1 1 /B7 /B6 /G7 /G6 /R7 /R6"
byte prefix = 0b11000000;
if ((blue & 0x80) == 0) prefix|= 0b00100000;
if ((blue & 0x40) == 0) prefix|= 0b00010000;
if ((green & 0x80) == 0) prefix|= 0b00001000;
if ((green & 0x40) == 0) prefix|= 0b00000100;
if ((red & 0x80) == 0) prefix|= 0b00000010;
if ((red & 0x40) == 0) prefix|= 0b00000001;
byte prefix = 0xC0 //first to bits are set
| (( ~blue &0xC0)>>2) //flip 2 most significant bits of r and move to protocol specified location
| (( ~green &0xC0)>>4) //flip 2 most significant bits of g and move to protocol specified location
| (( ~red &0xC0)>>6); //flip 2 most significant bits of b and move to protocol specified location

sendByte(prefix);

// Now must send the 3 colors
Expand Down