Add a "fork" of musl as //fusl.

fusl/arch/x86_64/atomic.h

+#ifndef _INTERNAL_ATOMIC_H
+#define _INTERNAL_ATOMIC_H
+
+#include <stdint.h>
+
+static inline int a_ctz_64(uint64_t x)
+{
+        __asm__( "bsf %1,%0" : "=r"(x) : "r"(x) );
+        return x;
+}
+
+static inline int a_ctz_l(unsigned long x)
+{
+        __asm__( "bsf %1,%0" : "=r"(x) : "r"(x) );
+        return x;
+}
+
+static inline void a_and_64(volatile uint64_t *p, uint64_t v)
+{
+        __asm__( "lock ; and %1, %0"
+                         : "=m"(*p) : "r"(v) : "memory" );
+}
+
+static inline void a_or_64(volatile uint64_t *p, uint64_t v)
+{
+        __asm__( "lock ; or %1, %0"
+                         : "=m"(*p) : "r"(v) : "memory" );
+}
+
+static inline void a_or_l(volatile void *p, long v)
+{
+        __asm__( "lock ; or %1, %0"
+                : "=m"(*(long *)p) : "r"(v) : "memory" );
+}
+
+static inline void *a_cas_p(volatile void *p, void *t, void *s)
+{
+        __asm__( "lock ; cmpxchg %3, %1"
+                : "=a"(t), "=m"(*(long *)p) : "a"(t), "r"(s) : "memory" );
+        return t;
+}
+
+static inline int a_cas(volatile int *p, int t, int s)
+{
+        __asm__( "lock ; cmpxchg %3, %1"
+                : "=a"(t), "=m"(*p) : "a"(t), "r"(s) : "memory" );
+        return t;
+}
+
+static inline void a_or(volatile int *p, int v)
+{
+        __asm__( "lock ; or %1, %0"
+                : "=m"(*p) : "r"(v) : "memory" );
+}
+
+static inline void a_and(volatile int *p, int v)
+{
+        __asm__( "lock ; and %1, %0"
+                : "=m"(*p) : "r"(v) : "memory" );
+}
+
+static inline int a_swap(volatile int *x, int v)
+{
+        __asm__( "xchg %0, %1" : "=r"(v), "=m"(*x) : "0"(v) : "memory" );
+        return v;
+}
+
+static inline int a_fetch_add(volatile int *x, int v)
+{
+        __asm__( "lock ; xadd %0, %1" : "=r"(v), "=m"(*x) : "0"(v) : "memory" );
+        return v;
+}
+
+static inline void a_inc(volatile int *x)
+{
+        __asm__( "lock ; incl %0" : "=m"(*x) : "m"(*x) : "memory" );
+}
+
+static inline void a_dec(volatile int *x)
+{
+        __asm__( "lock ; decl %0" : "=m"(*x) : "m"(*x) : "memory" );
+}
+
+static inline void a_store(volatile int *p, int x)
+{
+        __asm__( "mov %1, %0 ; lock ; orl $0,(%%rsp)" : "=m"(*p) : "r"(x) : "memory" );
+}
+
+static inline void a_spin()
+{
+        __asm__ __volatile__( "pause" : : : "memory" );
+}
+
+static inline void a_barrier()
+{
+        __asm__ __volatile__( "" : : : "memory" );
+}
+
+static inline void a_crash()
+{
+        __asm__ __volatile__( "hlt" : : : "memory" );
+}
+
+
+#endif