> Hi, > > I'm porting a driver, originally written in C, for an LCD to be used > with an embedded arm-processor (STM32). > The original driver uses SPI, my driver will use a USART in > synchronous > mode because the STM32 has no SPI for 9-bit. Unfortunately, the > bit-order is reversed between SPI and USART transmission. > Does anyone knows an efficient way to reverse bit-order of a byte for > the arm-processor ? I'm going to look into the assembly > language of the > arm-processor, but maybe someone knows this immediately. > For old processors like 8085 or Z80 I know how to do this, but > arm-assembler is new to me. > > Thanks for any hints. >
You might also look into the RBIT instruction which does this in one cpu cycle. See http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0489c/Cihjgdi d.html and applied to the STM32 USART http://forum.micromouseonline.com/viewtopic.php?f=7&t=460 Ludo _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
