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