FreeCalypso > hg > freecalypso-tools
view target-utils/libprintf/README @ 924:d452188587b4
rvinterf: begin change to backslash escape output format
Right now throughout the rvinterf suite, any time we emit output that
is expected to be ASCII, but may contain non-printable garbage, we use
'cat -v' form of garbage character representation. Unfortunately, this
transformation is lossy (can't be reversed 100% reliably in the user's
wetware), hence we would like to migrate to C-style backslash escapes,
including doubling of any already-present backslashes - this escape
mechanism is lossless. Begin this change by converting the output
of RV and L1 traces in rvinterf and rvtdump.
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Tue, 23 May 2023 03:10:50 +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).