From d960d4f2cbf18ff3476c7ac03698ec253885dd8e Mon Sep 17 00:00:00 2001
From: Rich Felker <dalias@aerifal.cx>
Date: Sun, 18 Sep 2011 16:44:54 -0400
Subject: initial commit of the arm port

this port assumes eabi calling conventions, eabi linux syscall
convention, and presence of the kernel helpers at 0xffff0f?0 needed
for threads support. otherwise it makes very few assumptions, and the
code should work even on armv4 without thumb support, as well as on
systems with thumb interworking. the bits headers declare this a
little endian system, but as far as i can tell the code should work
equally well on big endian.

some small details are probably broken; so far, testing has been
limited to qemu/aboriginal linux.
---
 arch/arm/atomic.h | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)
 create mode 100644 arch/arm/atomic.h

(limited to 'arch/arm/atomic.h')

diff --git a/arch/arm/atomic.h b/arch/arm/atomic.h
new file mode 100644
index 00000000..8dc31b2e
--- /dev/null
+++ b/arch/arm/atomic.h
@@ -0,0 +1,112 @@
+#ifndef _INTERNAL_ATOMIC_H
+#define _INTERNAL_ATOMIC_H
+
+#include <stdint.h>
+
+static inline int a_ctz_l(unsigned long x)
+{
+	static const char debruijn32[32] = {
+		0, 1, 23, 2, 29, 24, 19, 3, 30, 27, 25, 11, 20, 8, 4, 13,
+		31, 22, 28, 18, 26, 10, 7, 12, 21, 17, 9, 6, 16, 5, 15, 14
+	};
+	return debruijn32[(x&-x)*0x076be629 >> 27];
+}
+
+static inline int a_ctz_64(uint64_t x)
+{
+	uint32_t y = x;
+	if (!y) {
+		y = x>>32;
+		return 32 + a_ctz_l(y);
+	}
+	return a_ctz_l(y);
+}
+
+static inline int a_cas(volatile int *p, int t, int s)
+{
+	int old;
+	for (;;) {
+		if (!((int (*)(int, int, volatile int *))0xffff0fc0)(t, s, p))
+			return t;
+		if ((old=*p) != t)
+			return old;
+	}
+}
+
+static inline void *a_cas_p(volatile void *p, void *t, void *s)
+{
+	return (void *)a_cas(p, (int)t, (int)s);
+}
+
+static inline long a_cas_l(volatile void *p, long t, long s)
+{
+	return a_cas(p, t, s);
+}
+
+static inline int a_swap(volatile int *x, int v)
+{
+	int old;
+	do old = *x;
+	while (a_cas(x, old, v) != old);
+	return old;
+}
+
+static inline int a_fetch_add(volatile int *x, int v)
+{
+	int old;
+	do old = *x;
+	while (a_cas(x, old, old+v) != old);
+	return old;
+}
+
+static inline void a_inc(volatile int *x)
+{
+	a_fetch_add(x, 1);
+}
+
+static inline void a_dec(volatile int *x)
+{
+	a_fetch_add(x, -1);
+}
+
+static inline void a_store(volatile int *p, int x)
+{
+	*p=x;
+}
+
+static inline void a_spin()
+{
+}
+
+static inline void a_crash()
+{
+	*(volatile char *)0=0;
+}
+
+static inline void a_and(volatile int *p, int v)
+{
+	int old;
+	do old = *p;
+	while (a_cas(p, old, old&v) != old);
+}
+
+static inline void a_or(volatile int *p, int v)
+{
+	int old;
+	do old = *p;
+	while (a_cas(p, old, old|v) != old);
+}
+
+static inline void a_and_64(volatile uint64_t *p, uint64_t v)
+{
+	a_and((int *)p, v);
+	a_and((int *)p+1, v>>32);
+}
+
+static inline void a_or_64(volatile uint64_t *p, uint64_t v)
+{
+	a_or((int *)p, v);
+	a_or((int *)p+1, v>>32);
+}
+
+#endif
-- 
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