Added compile-time (macro) determiation of endianess shift needed for jr_state"s bitfield over xsubi. Reduces code size and removes 2 levels of indirection.

To switch to the old (still available, through the function"s symbol itself) ifunc implementation, build with `-D_RNGXX_JR_RESOLV_RUNTIME` (the resolution still happens at compile-time, but the ifunc impl demands indirection even if it does nothing.)

Fortune for rngxx's current commit: Future small blessing − 末小吉

src/rng/crand.c

@@ -33,7 +33,7 @@ _Static_assert( sizeof(uint48_t) == (sizeof(uint16_t) * 3), "bad uint48 (ushort[
 _Static_assert( sizeof(((struct jr_state*)NULL)->st) == sizeof(uint64_t), "bad uint64 (union st)");
 
 inline static unsigned short* IFUNC_DEF(_jr_st_resolv, (jr_xsub_t* restrict state)
-	__attribute__((const, nonnull, returns_nonnull)));
+	__attribute__((const, nonnull, returns_nonnull, access(none, 1))));
 
 inline static unsigned short* IFUNC_IMPL(_jr_st_resolv, low) (jr_xsub_t* restrict state)
 {
@@ -43,6 +43,17 @@ inline static unsigned short* IFUNC_IMPL(_jr_st_resolv, high) (jr_xsub_t* restri
 {
 	return state->xsubi+1;
 }
+
+inline static __attribute__((gnu_inline, const)) int _resv_is_high()
+{
+	static const struct jr_state chk = {
+		.st.xsubl = JR_MAX,
+	};
+	return chk.st._xsub 
+		? 1
+		: 0;
+}
+
 __attribute__((const))
 inline static unsigned short* IFUNC_RESOLVER(_jr_st_resolv) (jr_xsub_t* restrict state)
 {
@@ -57,7 +68,16 @@ inline static unsigned short* IFUNC_RESOLVER(_jr_st_resolv) (jr_xsub_t* restrict
 		? & IFUNC_NAME(_jr_st_resolv, high)
 		: & IFUNC_NAME(_jr_st_resolv, low);
 }
-
+#ifndef _RNGXX_JR_RESOLV_RUNTIME
+#define _jr_st_resolv_f (_resv_is_high() \
+				? & IFUNC_NAME(_jr_st_resolv, high) \
+				: & IFUNC_NAME(_jr_st_resolv, low))
+//unsigned short* (*const _jr_st_resolv_fp)(jr_xsub_t* restrict state) = _jr_st_resolv_f; // "not a constant expr ://
+
+#define _jr_st_resolv(st) _jr_st_resolv_f (st)
+#else
+#define _jr_st_resolv_f _jr_st_resolv
+#endif
 
 _fspec(readonly) internal long _jr_lastl(const struct jr_state* restrict state)
 {