Notes On Use Of Bit-Manipulation Instructions - Renesas Hitachi H8S/2194 Series Hardware Manual

2.6.5

Notes on Use of Bit-Manipulation Instructions

The BSET, BCLR, BNOT, BST, and BIST instructions read a byte of data, carry out bit
manipulation, then write back the byte of data. Caution is therefore required when using these
instructions on a register containing write-only bits, or a port.
The BCLR instruction can be used to clear internal I/O register flags to 0. In this case, the
relevant flag need not be read beforehand if it is clear that it has been set to 1 in an interrupt
handling routine, etc.
Rev. 2.0, 11/00, page 44 of 1037