1 files changed, 93 insertions, 0 deletions
diff --git a/user/lib/syscall.S b/user/lib/syscall.S
new file mode 100644
index 0000000..46fcb89
--- /dev/null
+++ b/user/lib/syscall.S
@@ -0,0 +1,93 @@
+/**
+** @file	ulibs.S
+**
+** @author	CSCI-452 class of 20245
+**
+** @brief	assembly-language user-level library functions
+*/
+
+#define	ASM_SRC
+
+// get the system call codes
+
+#include <syscalls.h>
+
+/**
+** System call stubs
+**
+** All have the same structure:
+**
+**      move a code into EAX
+**      generate the interrupt
+**      return to the caller
+**
+** As these are simple "leaf" routines, we don't use
+** the standard enter/leave method to set up a stack
+** frame - that takes time, and we don't really need it.
+**
+** Could be modified to use the UNIX/Linux convention of
+** having the syscall code set the 'C' flag to indicate that
+** the value being returned in %EAX is an error code:
+**
+**	  ...
+**	int	$VEC_SYSCALL
+**	jc	set_errno
+**	ret
+**	  ...
+**
+**	.globl	errno
+** set_errno:
+**	movl	%eax, errno
+**	movl	$-1, %eax
+**	ret
+*/
+
+#define	SYSCALL(name) \
+	.globl	name			; \
+name:					; \
+	movl	$SYS_##name, %eax	; \
+	int	$VEC_SYSCALL	; \
+	ret
+
+/*
+** "real" system calls
+*/
+
+SYSCALL(exit)
+SYSCALL(waitpid)
+SYSCALL(fork)
+SYSCALL(exec)
+SYSCALL(read)
+SYSCALL(write)
+SYSCALL(getpid)
+SYSCALL(getppid)
+SYSCALL(gettime)
+SYSCALL(getprio)
+SYSCALL(setprio)
+SYSCALL(kill)
+SYSCALL(sleep)
+
+/*
+** This is a bogus system call; it's here so that we can test
+** our handling of out-of-range syscall codes in the syscall ISR.
+*/
+SYSCALL(bogus)
+
+/*
+** Other library functions
+*/
+
+/**
+** fake_exit()
+**
+** Dummy "startup" function
+**
+** calls exit(%eax) - serves as the "return to" code for
+** main() functions, in case they don't call exit() themselves
+*/
+
+	.globl	fake_exit
+fake_exit:
+	// alternate: could push a "fake exit" status
+	pushl	%eax	// termination status returned by main()
+	call	exit	// terminate this process