util: Init half-float tables on demand.

Gets rid of unnecessary delays on startup and compiler-specific hax.

src/gallium/auxiliary/util/u_half.c

  */
 
 #include "util/u_half.h"
-#include "util/u_init.h"
 
 uint32_t util_half_to_float_mantissa_table[2048];
 uint32_t util_half_to_float_exponent_table[64];
 uint16_t util_float_to_half_base_table[512];
 uint8_t util_float_to_half_shift_table[512];
 
-static void util_half_init_tables(void)
+void util_half_init_tables(void)
 {
+    static boolean inited = FALSE;
 	int i;
 
+    if (inited) {
+        return;
+    }
+
 	/* zero */
 	util_half_to_float_mantissa_table[0] = 0;
 
 		util_float_to_half_base_table[256 + i] = util_float_to_half_base_table[i] | 0x8000;
 		util_float_to_half_shift_table[256 + i] = util_float_to_half_shift_table[i];
 	}
-}
 
-UTIL_INIT(util_half_init_tables);
+    inited = TRUE;
+}

src/gallium/auxiliary/util/u_half.h

 extern "C" {
 #endif
 
-
 extern uint32_t util_half_to_float_mantissa_table[2048];
 extern uint32_t util_half_to_float_exponent_table[64];
 extern uint32_t util_half_to_float_offset_table[64];
 extern uint16_t util_float_to_half_base_table[512];
 extern uint8_t util_float_to_half_shift_table[512];
 
+void util_half_init_tables(void);
+
 /*
  * Note that if the half float is a signaling NaN, the x87 FPU will turn
  * it into a quiet NaN immediately upon loading into a float.
 util_half_to_floatui(half h)
 {
 	unsigned exp = h >> 10;
+    util_half_init_tables();
 	return util_half_to_float_mantissa_table[util_half_to_float_offset_table[exp] + (h & 0x3ff)]
 		+ util_half_to_float_exponent_table[exp];
 }
 util_half_to_float(half h)
 {
 	union fi r;
+    util_half_init_tables();
 	r.ui = util_half_to_floatui(h);
 	return r.f;
 }
 util_floatui_to_half(uint32_t v)
 {
 	unsigned signexp = v >> 23;
+    util_half_init_tables();
 	return util_float_to_half_base_table[signexp]
 		+ ((v & 0x007fffff) >> util_float_to_half_shift_table[signexp]);
 }
 util_float_to_half(float f)
 {
 	union fi i;
+    util_half_init_tables();
 	i.f = f;
 	return util_floatui_to_half(i.ui);
 }

src/gallium/auxiliary/util/u_init.h

-/*
- * Copyright 2010 Luca Barbieri
- *
- * Permission is hereby granted, free of charge, to any person obtaining
- * a copy of this software and associated documentation files (the
- * "Software"), to deal in the Software without restriction, including
- * without limitation the rights to use, copy, modify, merge, publish,
- * distribute, sublicense, and/or sell copies of the Software, and to
- * permit persons to whom the Software is furnished to do so, subject to
- * the following conditions:
- *
- * The above copyright notice and this permission notice (including the
- * next paragraph) shall be included in all copies or substantial
- * portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
- * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
- * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
- * IN NO EVENT SHALL THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS BE
- * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
- * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
- * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
- *
- **************************************************************************/
-
-#ifndef U_INIT_H
-#define U_INIT_H
-
-/* Use UTIL_INIT(f) to have f called at program initialization.
-   Note that it is only guaranteed to be called if any symbol in the
-   .c file it is in sis referenced by the program.
-
-   UTIL_INIT functions are called in arbitrary order.
-*/
-
-#ifdef __cplusplus
-/* use a C++ global constructor */
-#define UTIL_INIT(f) struct f##__gctor_t {f##__gctor_t() {x();}} f##__gctor;
-#elif defined(_MSC_VER)
-/* add a pointer to the section where MSVC stores global constructor pointers */
-/* see http://blogs.msdn.com/vcblog/archive/2006/10/20/crt-initialization.aspx and
-   http://stackoverflow.com/questions/1113409/attribute-constructor-equivalent-in-vc */
-#pragma data_seg(".CRT$XCU")
-#define UTIL_INIT(f) static void __cdecl f##__init(void) {f();}; __declspec(allocate(".CRT$XCU")) void (__cdecl* f##__xcu)(void) = f##__init;
-#elif defined(__GNUC__)
-#define UTIL_INIT(f) static void f##__init(void) __attribute__((constructor)); static void f##__init(void) {f();}
-#else
-#error Unsupported compiler: please find out how to implement global initializers in C on it
-#endif
-
-#endif
-