FreeCalypso > hg > freecalypso-tools
view target-utils/libprintf/README @ 407:19e5a3e2f9c0
fcup-settime: moved time() retrieval a little closer to the output
A fundamental problem with all simple time transfer tools is that there is
always some delay between the time retrieval on the source system and that
transmitted time being set on the destination, and the resulting time
on the destination system is off by that delay amount. This delay cannot
be fully eliminated when working in a simple environment like ours,
but we should make our best effort to minimize it. In the present case,
moving the atinterf_init() call before the time() retrieval should make
a teensy-tiny improvement.
| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Sat, 11 Aug 2018 21:52:17 +0000 |
| parents | e7502631a0f9 |
| children |
line wrap: on
line source
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).