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-rw-r--r--asm/syscall.s22
1 files changed, 22 insertions, 0 deletions
diff --git a/asm/syscall.s b/asm/syscall.s
new file mode 100644
index 0000000..8860d89
--- /dev/null
+++ b/asm/syscall.s
@@ -0,0 +1,22 @@
+.global syscall
+
+// call from c with 4 x 32bit params
+// syscall number, p1,p2,p3,p4
+
+// TODO: push stack frame?
+
+syscall:
+
+ push %ebx // preserve (sysV abi convnetion)
+
+ mov 0x8(%esp),%eax //syscall number
+ mov 0xC(%esp),%edx //p1
+ mov 0x10(%esp),%ecx //p2
+ mov 0x14(%esp),%ebx //p3
+
+ int $0x80
+ mov %ebx, %eax // set as return value
+
+ pop %ebx // preserve
+ ret
+