removed system_time from atomic.S file and added it in a separate one.

git-svn-id: file:///srv/svn/repos/haiku/trunk/current@4332 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/kernel/libroot/os/arch/x86/system_time.S

@@ -0,0 +1,38 @@
+/*
+** Copyright 2001, Travis Geiselbrecht. All rights reserved.
+** Distributed under the terms of the NewOS License.
+*/
+
+#define FUNCTION(x) .global x; .type x,@function; x
+
+.text
+
+/* saves the conversion factor needed for system_time */
+cv_factor:
+	.word 0
+
+FUNCTION(setup_system_time):
+	movl	4(%esp),%eax
+	movl	%eax,cv_factor
+	ret
+
+/* long long system_time(); */
+FUNCTION(system_time):
+	/* load 64-bit factor into %eax (low), %edx (high) */
+	rdtsc		/* time in %edx,%eax */
+
+	pushl	%ebx
+	pushl	%ecx
+	movl	cv_factor, %ebx
+	movl	%edx, %ecx	/* save high half */
+	mull	%ebx 		/* truncate %eax, but keep %edx */
+	movl	%ecx, %eax
+	movl	%edx, %ecx	/* save high half of low */
+	mull	%ebx /*, %eax*/
+	/* now compute  [%edx, %eax] + [%ecx], propagating carry */
+	subl	%ebx, %ebx	/* need zero to propagate carry */
+	addl	%ecx, %eax
+	adc		%ebx, %edx
+	popl	%ecx
+	popl	%ebx
+	ret