FreeCalypso > hg > freecalypso-tools
view target-utils/libprintf/README @ 698:9ecbf1bf2e1b
fc-iram: added '+' to getopt magic string like in fc-xram
Both fc-iram and fc-xram now support secondary program invokation.
If the user needs to pass some options to the secondary program,
we don't want fc-iram or fc-xram to claim these options as its own,
thus we need to stop getopt() from reordering arguments. This fix
was already implemented in fc-xram a long time ago, but the issue
was overlooked when secondary program invokation ability was added
to fc-iram.
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Tue, 31 Mar 2020 03:23:26 +0000 |
parents | e7502631a0f9 |
children |
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The present libprintf is a very light printf implementation that is well-suited for simple bare-metal programs like loadagent; in the present case it overrides the much heavier printf implementation in newlib. Programs like the present loadagent only need printf in order to scribble on the serial console port, and the most sensible implementation is to have the "character output" function from the guts of printf point directly to the physical UART output routine, or a trivial wrapper that turns \n into \r\n. In contrast, newlib's version would pull in the complete FILE table infrastructure and malloc etc - maybe OK for more complex embedded programs that use those facilities for other things under a bona fide RTOS, but it would be disgusting to pull that stuff in for a minimal program like ours. The present printf implementation has been used earlier by the same author (Michael Spacefalcon) in the StarMON family of PowerPC bootloaders, and in my MC68x302-based SDSL CPE devices (Hack-o-Rocket and OSDCU).