skiboot changes:
- Added malloc lock
- Added a few functions
- Malloc will always 4 byte align everything
- Added asserts, requires core to provide abort()
WARNINGS:
- don't use free() on the result of memalign() (should be fixable)
Previous notes:
Standard C library for the SLOF firmware project
================================================
To use this library, link your target against the "libc.a" archive.
However, there are some prerequisites before you can use certain parts of the
library:
1) If you want to use malloc() and the like, you have to supply an implemen-
tation of sbrk() in your own code. malloc() uses sbrk() to get new, free
memory regions.
Prototype: void *sbrk(int incr);
Description: sbrk() increments the available data space by incr bytes and
returns a pointer to the start of the new area.
See the man-page of sbrk for details about this function.
2) Before you can use the stdio output functions like printf(), puts() and the
like, you have to provide a standard write() function in your code.
printf() and the like use write() to print out the strings to the standard
output.
Prototype: ssize_t write(int fd, const void *buf, size_t cnt);
Description: Write cnt byte from the buffer buf to the stream associated
with the file descriptor fd.
The stdio functions will print their output to the stdout channel which is
assigned with the file descriptor 1 by default. Note that the stdio
functions will not use open() before calling write(), so if the stdout
cannel needs to be opened first, you should do that in your start-up code
before using the libc functions for the first time.
3) Before you can use the stdio input functions like scanf() and the
like, you have to provide a standard read() function in your code.
scanf() and the like use read() to get the characters from the standard
input.
Prototype: ssize_t read(int fd, void *buf, size_t cnt);
Description: Read cnt byte from the stream associated with the file
descriptor fd and put them into the buffer buf.
The stdio functions will get their input from the stdin channel which is
assigned with the file descriptor 0 by default. Note that the stdio
functions will not use open() before calling read(), so if the stdin
cannel needs to be opened first, you should do that in your start-up code
before using the libc functions for the first time.
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