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

fusl/arch/sh/atomic.h

+#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);
+}
+
+#define LLSC_CLOBBERS "r0", "t", "memory"
+#define LLSC_START(mem) "synco\n"  \
+        "0:     movli.l @" mem ", r0\n"
+#define LLSC_END(mem)              \
+        "1:     movco.l r0, @" mem "\n"    \
+        "       bf 0b\n"                   \
+        "       synco\n"
+
+static inline int __sh_cas_llsc(volatile int *p, int t, int s)
+{
+        int old;
+        __asm__ __volatile__(
+                LLSC_START("%1")
+                "       mov r0, %0\n"
+                "       cmp/eq %0, %2\n"
+                "       bf 1f\n"
+                "       mov %3, r0\n"
+                LLSC_END("%1")
+                : "=&r"(old) : "r"(p), "r"(t), "r"(s) : LLSC_CLOBBERS);
+        return old;
+}
+
+static inline int __sh_swap_llsc(volatile int *x, int v)
+{
+        int old;
+        __asm__ __volatile__(
+                LLSC_START("%1")
+                "       mov r0, %0\n"
+                "       mov %2, r0\n"
+                LLSC_END("%1")
+                : "=&r"(old) : "r"(x), "r"(v) : LLSC_CLOBBERS);
+        return old;
+}
+
+static inline int __sh_fetch_add_llsc(volatile int *x, int v)
+{
+        int old;
+        __asm__ __volatile__(
+                LLSC_START("%1")
+                "       mov r0, %0\n"
+                "       add %2, r0\n"
+                LLSC_END("%1")
+                : "=&r"(old) : "r"(x), "r"(v) : LLSC_CLOBBERS);
+        return old;
+}
+
+static inline void __sh_store_llsc(volatile int *p, int x)
+{
+        __asm__ __volatile__(
+                "       synco\n"
+                "       mov.l %1, @%0\n"
+                "       synco\n"
+                : : "r"(p), "r"(x) : "memory");
+}
+
+static inline void __sh_and_llsc(volatile int *x, int v)
+{
+        __asm__ __volatile__(
+                LLSC_START("%0")
+                "       and %1, r0\n"
+                LLSC_END("%0")
+                : : "r"(x), "r"(v) : LLSC_CLOBBERS);
+}
+
+static inline void __sh_or_llsc(volatile int *x, int v)
+{
+        __asm__ __volatile__(
+                LLSC_START("%0")
+                "       or %1, r0\n"
+                LLSC_END("%0")
+                : : "r"(x), "r"(v) : LLSC_CLOBBERS);
+}
+
+#ifdef __SH4A__
+#define a_cas(p,t,s)     __sh_cas_llsc(p,t,s)
+#define a_swap(x,v)      __sh_swap_llsc(x,v)
+#define a_fetch_add(x,v) __sh_fetch_add_llsc(x, v)
+#define a_store(x,v)     __sh_store_llsc(x, v)
+#define a_and(x,v)       __sh_and_llsc(x, v)
+#define a_or(x,v)        __sh_or_llsc(x, v)
+#else
+
+int  __sh_cas(volatile int *, int, int);
+int  __sh_swap(volatile int *, int);
+int  __sh_fetch_add(volatile int *, int);
+void __sh_store(volatile int *, int);
+void __sh_and(volatile int *, int);
+void __sh_or(volatile int *, int);
+
+#define a_cas(p,t,s)     __sh_cas(p,t,s)
+#define a_swap(x,v)      __sh_swap(x,v)
+#define a_fetch_add(x,v) __sh_fetch_add(x, v)
+#define a_store(x,v)     __sh_store(x, v)
+#define a_and(x,v)       __sh_and(x, v)
+#define a_or(x,v)        __sh_or(x, v)
+#endif
+
+static inline void *a_cas_p(volatile void *p, void *t, void *s)
+{
+        return (void *)a_cas(p, (int)t, (int)s);
+}
+
+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);
+}
+
+#define a_spin a_barrier
+
+static inline void a_barrier()
+{
+        a_cas(&(int){0}, 0, 0);
+}
+
+static inline void a_crash()
+{
+        *(volatile char *)0=0;
+}
+
+static inline void a_or_l(volatile void *p, long v)
+{
+        a_or(p, v);
+}
+
+static inline void a_and_64(volatile uint64_t *p, uint64_t v)
+{
+        union { uint64_t v; uint32_t r[2]; } u = { v };
+        a_and((int *)p,   u.r[0]);
+        a_and((int *)p+1, u.r[1]);
+}
+
+static inline void a_or_64(volatile uint64_t *p, uint64_t v)
+{
+        union { uint64_t v; uint32_t r[2]; } u = { v };
+        a_or((int *)p,   u.r[0]);
+        a_or((int *)p+1, u.r[1]);
+}
+
+#endif