[fpc-devel] FPC micro controller
Marco van de Voort
marcov at stack.nl
Thu Jul 30 12:15:16 CEST 2009
In our previous episode, Desmond Coertzen said:
> No use for OS, just for smaller MCU's that are bit accessible.
> By application I meant: Is this the correct method to apply a bit-packed
> structure to code?
Note that there are two kinds of bitaccessibility.
E.g. microchip follows more the bitpacked way, where all SFR are overlayed
(ABSOLUTE in FPC) with a bitpacked union in the header.
In addition some mcu's like IIRC 8051 (*) allows to access ANY integer/byte
value to be accessed using .<bitnr> suffix. So if b is of type byte, b.7
returns the 7th bit. It also had a special type bit to store these and do
some limited arithmetic on them. Probably mapping directly on some bit sized
registers/flags and instructions.
(*) iirc we had some Hitachi clone 80515 or so. The compiler was the fairly
wellknown Keile one.
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