1 files changed, 95 insertions, 0 deletions
diff --git a/dhrystone/syscalls.c b/dhrystone/syscalls.c
new file mode 100644
index 0000000..cdf872f
--- /dev/null
+++ b/dhrystone/syscalls.c
@@ -0,0 +1,95 @@
+// 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();
+}
+