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adding newlib0 example
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‎newlib0/Makefile

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ARMGNU ?= arm-none-eabi
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COPS = -Wall -O2 -nostartfiles -ffreestanding
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LIB = -L /opt/gnuarm/arm-none-eabi/lib/ -L/opt/gnuarm/lib/gcc/arm-none-eabi/4.7.2
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gcc : uart02.hex uart02.bin
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all : gcc
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clean :
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rm -f *.o
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rm -f *.bin
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rm -f *.hex
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rm -f *.elf
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rm -f *.list
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rm -f *.img
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rm -f *.bc
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rm -f *.clang.opt.s
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vectors.o : vectors.s
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$(ARMGNU)-as vectors.s -o vectors.o
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uart02.o : uart02.c
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$(ARMGNU)-gcc $(COPS) -c uart02.c -o uart02.o
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uart02.elf : memmap vectors.o uart02.o syscalls.o
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$(ARMGNU)-ld vectors.o uart02.o syscalls.o -T memmap -o uart02.elf $(LIB) -lc -lgcc
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$(ARMGNU)-objdump -D uart02.elf > uart02.list
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uart02.bin : uart02.elf
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$(ARMGNU)-objcopy uart02.elf -O binary uart02.bin
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uart02.hex : uart02.elf
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$(ARMGNU)-objcopy uart02.elf -O ihex uart02.hex
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syscalls.o : syscalls.c
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$(ARMGNU)-gcc $(COPS) -c $(COPS) syscalls.c -o syscalls.o
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‎newlib0/README

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Somewhat threw this together.
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I have not tried newlib in a while, for a while there it was quite
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difficult to get a combination of binutils, gcc and newlib that would
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build crosscompiled. Somewhat trivial now.
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went here
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ftp://sources.redhat.com/pub/newlib/index.html
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downloaded newlib-1.20.0.tar.gz
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untarred it
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since I already had a gnu toolchain I built using the scripts in my
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build_gcc that I built to /opt/gnuarm
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tar xzvf newlib-1.20.0.tar.gz
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cd newlib-1.20.0
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-- now here is my solution
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cd newlib/libc/sys/arm/
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mv syscalls.c syscalls.corig
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touch syscalls.c
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mv libcfunc.c libcfunc.corig
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touch libcfunc.c
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mv crt0.S crt0.Sorig
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touch crt0.S
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cd ../../../../
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-- should be back in the newlib-1.20.0 directory
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./configure --target=arm-none-eabi --prefix=/opt/gnuarm
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make
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make install
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what I would then do is go into syscalls and start pruning, make all
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the functions return whatever the proper flavor of success was. to
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get printf to work you need isatty to return the right thing. note
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I also have a functional malloc here by defining the beginning of my
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heap and doing trivial memory management.
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The way I used to do all of this is based on something I learned from
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others, before building gcc pull in the proper newlib directories
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and then build gcc with the right headers and newlib stuff and it
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would build it all into one nice package (when it worked) so you didnt
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have to specify lib paths. Since I threw this together I had to specify
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the lib paths to things you will need to fix those paths for yours.
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The reason why I neutered the three files in newlib is it is a quick and
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easy way to allow the newlib makefile to continue without complaint but
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also to allow the project to own those system calls. Since I run bare
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metal each project may want to do something different. If this were an
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operating system use of newlib then I would consider one solution for
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everyone and have it built into the normal place.
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I had to fight the linker a little to get the right code in the right
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place. Be careful to check your disassembly of your binary so that
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you know that your start code is at the beginning of your image not
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somewhere after crti or crtbegin or something like that.
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you should see
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...
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12345678
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0000800C
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Hello World!
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0x0000800C
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32780
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If it all works. for now I will not leave binaries in the repo even
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though I expect this is a challenging build for many.

‎newlib0/memmap

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MEMORY
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{
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ram : ORIGIN = 0x8000, LENGTH = 0x20000
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}
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SECTIONS
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{
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.text : { *(.text*) } > ram
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.bss : { *(.bss*) } > ram
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}
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‎newlib0/syscalls.c

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/* Support files for GNU libc. Files in the system namespace go here.
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Files in the C namespace (ie those that do not start with an
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underscore) go in .c. */
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#include <_ansi.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/fcntl.h>
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#include <stdio.h>
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#include <time.h>
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#include <sys/time.h>
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#include <sys/times.h>
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#include <errno.h>
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#include <reent.h>
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void uart_putc ( unsigned int c );
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unsigned int heap_end=0x0020000;
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unsigned int prev_heap_end;
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/* Forward prototypes. */
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int _system _PARAMS ((const char *));
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int _rename _PARAMS ((const char *, const char *));
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int isatty _PARAMS ((int));
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clock_t _times _PARAMS ((struct tms *));
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int _gettimeofday _PARAMS ((struct timeval *, struct timezone *));
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void _raise _PARAMS ((void));
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int _unlink _PARAMS ((void));
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int _link _PARAMS ((void));
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int _stat _PARAMS ((const char *, struct stat *));
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int _fstat _PARAMS ((int, struct stat *));
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caddr_t _sbrk _PARAMS ((int));
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int _getpid _PARAMS ((int));
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int _kill _PARAMS ((int, int));
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void _exit _PARAMS ((int));
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int _close _PARAMS ((int));
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int _open _PARAMS ((const char *, int, ...));
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int _write _PARAMS ((int, char *, int));
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int _lseek _PARAMS ((int, int, int));
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int _read _PARAMS ((int, char *, int));
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void initialise_monitor_handles _PARAMS ((void));
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//static int
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//remap_handle (int fh)
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//{
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//return 0;
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//}
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void
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initialise_monitor_handles (void)
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{
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}
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//static int
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//get_errno (void)
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//{
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//return(0);
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//}
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//static int
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//error (int result)
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//{
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//errno = get_errno ();
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//return result;
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//}
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int
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_read (int file,
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char * ptr,
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int len)
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{
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return len;
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}
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int
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_lseek (int file,
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int ptr,
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int dir)
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{
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return 0;
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}
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int
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_write (int file,
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char * ptr,
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int len)
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{
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int r;
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for(r=0;r<len;r++) uart_putc(ptr[r]);
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return len;
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}
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int
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_open (const char * path,
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int flags,
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...)
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{
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return 0;
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}
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int
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_close (int file)
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{
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return 0;
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}
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void
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_exit (int n)
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{
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while(1);
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}
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int
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_kill (int n, int m)
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{
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return(0);
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}
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int
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_getpid (int n)
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{
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return 1;
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n = n;
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}
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caddr_t
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_sbrk (int incr)
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{
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prev_heap_end = heap_end;
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heap_end += incr;
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return (caddr_t) prev_heap_end;
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}
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int
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_fstat (int file, struct stat * st)
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{
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return 0;
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}
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int _stat (const char *fname, struct stat *st)
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{
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return 0;
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}
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int
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_link (void)
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{
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return -1;
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}
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int
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_unlink (void)
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{
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return -1;
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}
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void
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_raise (void)
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{
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return;
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}
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int
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_gettimeofday (struct timeval * tp, struct timezone * tzp)
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{
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if(tp)
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{
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tp->tv_sec = 10;
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tp->tv_usec = 0;
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}
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if (tzp)
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{
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tzp->tz_minuteswest = 0;
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tzp->tz_dsttime = 0;
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}
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return 0;
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}
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clock_t
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_times (struct tms * tp)
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{
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clock_t timeval;
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timeval = 10;
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if (tp)
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{
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tp->tms_utime = timeval; /* user time */
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tp->tms_stime = 0; /* system time */
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tp->tms_cutime = 0; /* user time, children */
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tp->tms_cstime = 0; /* system time, children */
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}
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return timeval;
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};
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int
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_isatty (int fd)
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{
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return 1;
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fd = fd;
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}
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int
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_system (const char *s)
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{
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if (s == NULL)
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return 0;
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errno = ENOSYS;
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return -1;
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}
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int
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_rename (const char * oldpath, const char * newpath)
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{
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errno = ENOSYS;
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return -1;
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}

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