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Hello Flow Code Community,

may some one could help me please. I´ll try to use the follwing MSB-LSB Bit swop with ESP32:

DATACRC = (DATACRC >> 7) & 1 | (DATACRC >> 5) & 2 | (DATACRC >> 3) & 4 | (DATACRC >> 1) & 8 | (DATACRC << 1) & 0x10 | (DATACRC << 3) & 0x20 | (DATACRC << 5) & 0x40 | (DATACRC << 7) & 0x80

Unfortunately with this calculation I can not compile to ESP32. With my PIC 18Fxxxx Controler I never had a compile problem with this calculation.

May somebody can teach me how to modify.

BR
Dirk

OK found the problem by my self. Missing brackets were the problem. Here ist the correct version:

DATACRC = ((DATACRC >> 7) & 0x01) |
((DATACRC >> 5) & 0x02) |
((DATACRC >> 3) & 0x04) |
((DATACRC >> 1) & 0x08) |
((DATACRC << 1) & 0x10) |
((DATACRC << 3) & 0x20) |
((DATACRC << 5) & 0x40) |
((DATACRC << 7) & 0x80);

There are some interesting algorithms:

Depending on how often you need to reverse the bits of a byte 0 - the quickest technique is probably a lookup table rev[256]

Where :
rev[0] = 0
rev[1] = 0x80
rev[2] = 0x40
etc

Then to reverse a byte rev_byte = rev[byte].

See also Hacker's Delight (Henry S Warren Jr)

Martin