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/**
** @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
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