From fd69eb2b35864ad22752a470a46b13b098286b59 Mon Sep 17 00:00:00 2001
From: Chia-I Wu <olvaffe@gmail.com>
Date: Mon, 18 Aug 2014 14:39:31 +0800
Subject: icd: add more utils for working with floats

---
 icd/common/CMakeLists.txt |  2 +-
 icd/common/icd-utils.c    | 83 +++++++++++++++++++++++++++++++++++++++++++++++
 icd/common/icd-utils.h    | 25 ++++++++++++++
 3 files changed, 109 insertions(+), 1 deletion(-)
 create mode 100644 icd/common/icd-utils.c

diff --git a/icd/common/CMakeLists.txt b/icd/common/CMakeLists.txt
index 7c8e8352..ba49a230 100644
--- a/icd/common/CMakeLists.txt
+++ b/icd/common/CMakeLists.txt
@@ -9,5 +9,5 @@ add_custom_command(OUTPUT icd-dispatch-entrypoints.c
 	           DEPENDS ${PROJECT_SOURCE_DIR}/xgl-generate.py
 	                   ${PROJECT_SOURCE_DIR}/xgl.py)
 
-add_library(icd OBJECT icd.c icd-dispatch-entrypoints.c icd-dispatch-table.h icd-format.c)
+add_library(icd OBJECT icd.c icd-dispatch-entrypoints.c icd-dispatch-table.h icd-format.c icd-utils.c)
 set_target_properties(icd PROPERTIES POSITION_INDEPENDENT_CODE ON)
diff --git a/icd/common/icd-utils.c b/icd/common/icd-utils.c
new file mode 100644
index 00000000..2c0b8707
--- /dev/null
+++ b/icd/common/icd-utils.c
@@ -0,0 +1,83 @@
+/*
+ * XGL
+ *
+ * Copyright (C) 2014 LunarG, Inc.
+ *
+ * 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 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 AUTHORS OR COPYRIGHT HOLDERS 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.
+ */
+
+#include "icd-utils.h"
+
+/* stolen from Mesa */
+uint16_t u_float_to_half(float f)
+{
+    union fi {
+        float f;
+        uint32_t ui;
+    };
+
+   uint32_t sign_mask  = 0x80000000;
+   uint32_t round_mask = ~0xfff;
+   uint32_t f32inf = 0xff << 23;
+   uint32_t f16inf = 0x1f << 23;
+   uint32_t sign;
+   union fi magic;
+   union fi f32;
+   uint16_t f16;
+
+   magic.ui = 0xf << 23;
+
+   f32.f = f;
+
+   /* Sign */
+   sign = f32.ui & sign_mask;
+   f32.ui ^= sign;
+
+   if (f32.ui == f32inf) {
+      /* Inf */
+      f16 = 0x7c00;
+   } else if (f32.ui > f32inf) {
+      /* NaN */
+      f16 = 0x7e00;
+   } else {
+      /* Number */
+      f32.ui &= round_mask;
+      f32.f  *= magic.f;
+      f32.ui -= round_mask;
+
+      /*
+       * Clamp to max finite value if overflowed.
+       * OpenGL has completely undefined rounding behavior for float to
+       * half-float conversions, and this matches what is mandated for float
+       * to fp11/fp10, which recommend round-to-nearest-finite too.
+       * (d3d10 is deeply unhappy about flushing such values to infinity, and
+       * while it also mandates round-to-zero it doesn't care nearly as much
+       * about that.)
+       */
+      if (f32.ui > f16inf)
+         f32.ui = f16inf - 1;
+
+      f16 = f32.ui >> 13;
+   }
+
+   /* Sign */
+   f16 |= sign >> 16;
+
+   return f16;
+}
diff --git a/icd/common/icd-utils.h b/icd/common/icd-utils.h
index c6008520..26f911e2 100644
--- a/icd/common/icd-utils.h
+++ b/icd/common/icd-utils.h
@@ -25,6 +25,8 @@
 #ifndef ICD_UTILS_H
 #define ICD_UTILS_H
 
+#include <stdbool.h>
+#include <stdint.h>
 #include <assert.h>
 #include "icd.h"
 
@@ -34,6 +36,9 @@
     (void) sizeof(char[1 - 2 * !(expr)]);   \
 } while (0)
 
+#define U_CLAMP(val, min, max) \
+    ((val) < (min) ? (min) : (val) > (max)? (max) : (val))
+
 /**
  * Return true if val is power of two, or zero.
  */
@@ -53,4 +58,24 @@ static inline unsigned int u_minify(unsigned int val, unsigned level)
     return (val >> level) ? val >> level : 1;
 }
 
+static inline uint32_t u_fui(float f)
+{
+    union {
+        float f;
+        uint32_t ui;
+    } u = { .f = f };
+
+    return u.ui;
+}
+
+static inline int u_iround(float f)
+{
+    if (f >= 0.0f)
+        return (int) (f + 0.5f);
+    else
+        return (int) (f - 0.5f);
+}
+
+uint16_t u_float_to_half(float f);
+
 #endif /* ICD_UTILS_H */
-- 
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