Fix incorrect uint48_t sizing.

Resolve xsubi via ifunc if bitfield is placed in unexpected location within union.

Fortune for cpprng's current commit: Middle blessing − 中吉

include/common.h

@@ -9,7 +9,6 @@ extern "C" {
 #include <stddef.h>
 #include <stdlib.h>
 
-
 #define DEF(s, n) typedef s ## int ## n ## _t s ## n
 #define DEFINT(n) typedef uint ## n ## _t u ## n; \
 		  typedef int ## n ## _t i ## n

include/rng/crand.h

@@ -9,8 +9,5 @@ namespace rng
 	{
 	
 	private:
-		struct _inner;
-		// XXX: FUCK: This doesn't fucking work...
-		mem::aligned_ptr<jr_state> _state;
 	};
 }

src/rng/crand.c

@@ -1,8 +1,14 @@
 #include <stdlib.h>
 #include <string.h>
+#include <time.h>
+#include <assert.h>
+#include <stdio.h>
 
 #include "crand.h"
 
+typedef unsigned short uint48_t[3];
+
+
 struct jr_state
 {
 	long result;
@@ -10,22 +16,46 @@ struct jr_state
 	union {
 		unsigned short xsubi[3];
 		struct {
-			unsigned int   xsubh : 24;
+			uint64_t   xsubh : 48;
-			unsigned char  _xsub : 8;
+			uint16_t  _xsub  : 16;
 		};
-		unsigned int xsubl;
+		uint64_t xsubl;
 	} st;
 };
+_Static_assert( sizeof(uint48_t) == (sizeof(uint16_t) * 3), "bad uint48 (ushort[3])");
+_Static_assert( sizeof(((struct jr_state*)NULL)->st) == sizeof(uint64_t), "bad uint64 (union st)");
+
+static unsigned short* _impl__jr_st_resolv__low(struct jr_state* restrict state)
+{
+	return state->st.xsubi;
+}
 
-void _jr_seed(struct jr_state* restrict state, unsigned int with)
+static unsigned short* _impl__jr_st_resolv__high(struct jr_state* restrict state)
+{
+	return state->st.xsubi+1;
+}
+
+static unsigned short* (*_ifun__jr_st_resolv (void)) (struct jr_state* restrict state)
+{
+	struct jr_state chk = {0};
+	chk.st.xsubh = JR_MAX;
+	return chk.st._xsub 
+		? &_impl__jr_st_resolv__high
+		: &_impl__jr_st_resolv__low;
+}
+
+static unsigned short* _jr_st_resolv(struct jr_state* restrict state)
+	__attribute__((ifunc("_ifun__jr_st_resolv")));
+
+void _jr_seed(struct jr_state* restrict state, unsigned long with)
 {
 	state->st.xsubh = with;
-	seed48_r(state->st.xsubi, &state->data);
+	seed48_r(_jr_st_resolv(state), &state->data);
 }
 
 long _jr_proc(struct jr_state* restrict state)
 {
-	jrand48_r(state->st.xsubi, &state->data, &state->result);
+	jrand48_r(_jr_st_resolv(state), &state->data, &state->result);
 	return state->result;
 }
 
@@ -41,3 +71,41 @@ void _jr_free(struct jr_state* restrict state)
 {
 	free(state);
 }
+
+//TODO: Use test macros from tracemac, run with attr(ctor) if `-DTEST` is provided.
+void __TEST__jr_test()
+{
+	struct jr_state* st = _jr_alloc();
+	assert(!st->st._xsub);
+	_jr_seed(st, ~0UL);
+	const volatile unsigned short* res_state = _jr_st_resolv(st);
+	printf("seeded: %lu (full %lu, spill %u). xsubi = [%04x, %04x, %04x) %04x], resolv = [%04x, %04x, %04x) %04x]\n", (uint64_t)st->st.xsubh, st->st.xsubl, st->st._xsub,
+				st->st.xsubi[0],
+				st->st.xsubi[1],
+				st->st.xsubi[2],
+				st->st.xsubi[3],
+
+				res_state[0],
+				res_state[1],
+				res_state[2],
+				res_state[3]);
+	assert(!st->st._xsub);
+	for(int i=0;i<10;i++)
+	{
+		printf("res: %ld\n", _jr_proc(st));
+		printf("state: %lu (full %lu, spill %u). xsubi = %p, resolv = %p\n", (uint64_t)st->st.xsubh, st->st.xsubl, st->st._xsub,
+					(const void*)st->st.xsubi, (const void*)_jr_st_resolv(st));
+	}
+	printf("ended: %lu (full %lu, spill %u). xsubi = [%04x, %04x, %04x) %04x], resolv = [%04x, %04x, %04x) %04x]\n", (uint64_t)st->st.xsubh, st->st.xsubl, st->st._xsub,
+				st->st.xsubi[0],
+				st->st.xsubi[1],
+				st->st.xsubi[2],
+				st->st.xsubi[3],
+
+				res_state[0],
+				res_state[1],
+				res_state[2],
+				res_state[3]);
+	assert(!st->st._xsub);
+	_jr_free(st);
+}

src/rng/crand.cpp

@@ -6,10 +6,10 @@
 
 namespace rng
 {
-	struct crand::_inner {
+	//struct crand::_inner {
-		
+	//	
-		jr_state st;
+	//	jr_state st;
-	};
+	//};
 	
 //TODO: Make header for rng::crand, a derived type of `Random`.
 }

src/rng/crand.h

@@ -3,7 +3,7 @@
 
 #include <common.h>
 
-#define JR_MAX (UINT32_MAX >> 8)
+#define JR_MAX (UINT64_MAX >> 16)
 
 #ifdef __cplusplus
 extern "C" {
@@ -13,7 +13,7 @@ struct jr_state;
 
 //TODO: make all these functions visibility("internal")
 
-void _jr_seed(struct jr_state* restrict state, unsigned int with);
+void _jr_seed(struct jr_state* restrict state, unsigned long with);
 long _jr_proc(struct jr_state* restrict state);
 struct jr_state* _jr_alloc();
 void _jr_free(struct jr_state* restrict state);