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// An extremely minimalist syscalls.c for newlib
// Based on riscv newlib libgloss/riscv/machine/syscall.h
// Written by Clifford Wolf.
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>
#define UNIMPL_FUNC(_f) ".globl " #_f "\n.type " #_f ", @function\n" #_f ":\n"
asm (
".text\n"
".align 2\n"
UNIMPL_FUNC(open)
UNIMPL_FUNC(openat)
UNIMPL_FUNC(lseek)
UNIMPL_FUNC(stat)
UNIMPL_FUNC(lstat)
UNIMPL_FUNC(fstatat)
UNIMPL_FUNC(isatty)
UNIMPL_FUNC(access)
UNIMPL_FUNC(faccessat)
UNIMPL_FUNC(link)
UNIMPL_FUNC(unlink)
UNIMPL_FUNC(execve)
UNIMPL_FUNC(getpid)
UNIMPL_FUNC(fork)
UNIMPL_FUNC(kill)
UNIMPL_FUNC(wait)
UNIMPL_FUNC(times)
UNIMPL_FUNC(gettimeofday)
UNIMPL_FUNC(ftime)
UNIMPL_FUNC(utime)
UNIMPL_FUNC(chown)
UNIMPL_FUNC(chmod)
UNIMPL_FUNC(chdir)
UNIMPL_FUNC(getcwd)
UNIMPL_FUNC(sysconf)
"j unimplemented_syscall\n"
);
void unimplemented_syscall()
{
const char *p = "Unimplemented system call called!\n";
while (*p)
*(volatile int*)0x10000000 = *(p++);
asm volatile ("ebreak");
__builtin_unreachable();
}
ssize_t read(int file, void *ptr, size_t len)
{
// always EOF
return 0;
}
ssize_t write(int file, const void *ptr, size_t len)
{
const void *eptr = ptr + len;
while (ptr != eptr)
*(volatile int*)0x10000000 = *(char*)(ptr++);
return len;
}
int close(int file)
{
// close is called before _exit()
return 0;
}
int fstat(int file, struct stat *st)
{
// fstat is called during libc startup
errno = ENOENT;
return -1;
}
void *sbrk(ptrdiff_t incr)
{
extern unsigned char _end[]; // Defined by linker
static unsigned long heap_end;
if (heap_end == 0)
heap_end = (long)_end;
heap_end += incr;
return (void *)(heap_end - incr);
}
void _exit(int exit_status)
{
asm volatile ("ebreak");
__builtin_unreachable();
}
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