From 5fc298964b76d6770f54b74a8456869c929a57f0 Mon Sep 17 00:00:00 2001
From: Sam Hocevar <sam@hocevar.net>
Date: Tue, 20 Sep 2011 12:03:55 +0000
Subject: [PATCH] core: start working on a "real" class for arbitrarily sized
 floats.

---
 src/Makefile.am  |  1 +
 src/core.h       |  1 +
 src/real.cpp     | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/real.h       | 42 ++++++++++++++++++++++++++++++++++++++++++
 test/Makefile.am |  2 +-
 5 files changed, 93 insertions(+), 1 deletion(-)
 create mode 100644 src/real.cpp
 create mode 100644 src/real.h

diff --git a/src/Makefile.am b/src/Makefile.am
index eb1b157a..886558d2 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -11,6 +11,7 @@ liblol_a_SOURCES = \
     text.cpp text.h emitter.cpp emitter.h numeric.h hash.cpp hash.h \
     worldentity.cpp worldentity.h gradient.cpp gradient.h half.cpp half.h \
     platform.cpp platform.h sprite.cpp sprite.h trig.cpp trig.h \
+    real.cpp real.h \
     \
     lol/unit.h \
     \
diff --git a/src/core.h b/src/core.h
index 55a18d37..feefb6fc 100644
--- a/src/core.h
+++ b/src/core.h
@@ -64,6 +64,7 @@ static inline int isnan(float f)
 // Base types
 #include "trig.h"
 #include "half.h"
+#include "real.h"
 #include "matrix.h"
 #include "numeric.h"
 #include "timer.h"
diff --git a/src/real.cpp b/src/real.cpp
new file mode 100644
index 00000000..dfe0bd52
--- /dev/null
+++ b/src/real.cpp
@@ -0,0 +1,48 @@
+//
+// Lol Engine
+//
+// Copyright: (c) 2010-2011 Sam Hocevar <sam@hocevar.net>
+//   This program is free software; you can redistribute it and/or
+//   modify it under the terms of the Do What The Fuck You Want To
+//   Public License, Version 2, as published by Sam Hocevar. See
+//   http://sam.zoy.org/projects/COPYING.WTFPL for more details.
+//
+
+#if defined HAVE_CONFIG_H
+#   include "config.h"
+#endif
+
+#include <cstring>
+
+#include "core.h"
+
+using namespace std;
+
+namespace lol
+{
+
+template<> real4k::Real(float f)
+{
+    union { float f; uint32_t x; } u = { f };
+
+    uint32_t sign = u.x & 0x80000000u;
+    int e = ((u.x >> 23) & 0xff) + (1 << 30) - (1 << 10);
+
+    m_signexp = sign | e;
+    m_mantissa[0] = u.x << 17;
+    memset(m_mantissa + 1, 0, sizeof(m_mantissa) - sizeof(m_mantissa[0]));
+}
+
+template<> real4k::operator float() const
+{
+    union { float f; uint32_t x; } u;
+
+    u.x = m_mantissa[0] >> 17;
+    u.x |= ((m_signexp & 0x7fffffffu) - (1 << 30) + (1 << 10)) << 23;
+    u.x |= m_signexp & 0x80000000u;
+
+    return u.f;
+}
+
+} /* namespace lol */
+
diff --git a/src/real.h b/src/real.h
new file mode 100644
index 00000000..d31238c3
--- /dev/null
+++ b/src/real.h
@@ -0,0 +1,42 @@
+//
+// Lol Engine
+//
+// Copyright: (c) 2010-2011 Sam Hocevar <sam@hocevar.net>
+//   This program is free software; you can redistribute it and/or
+//   modify it under the terms of the Do What The Fuck You Want To
+//   Public License, Version 2, as published by Sam Hocevar. See
+//   http://sam.zoy.org/projects/COPYING.WTFPL for more details.
+//
+
+//
+// The Real class
+// --------------
+//
+
+#if !defined __LOL_REAL_H__
+#define __LOL_REAL_H__
+
+#include <stdint.h>
+
+namespace lol
+{
+
+template<int NBITS> class Real
+{
+public:
+    inline Real<NBITS>() {}
+    Real<NBITS>(float f);
+
+    operator float() const;
+
+private:
+    uint32_t m_signexp;
+    uint32_t m_mantissa[(NBITS + 31) / 32];
+};
+
+typedef Real<4096> real4k;
+
+} /* namespace lol */
+
+#endif // __LOL_REAL_H__
+
diff --git a/test/Makefile.am b/test/Makefile.am
index 23e654fa..0ffe132e 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -19,7 +19,7 @@ noinst_PROGRAMS = quad sandbox benchsuite testsuite
 TESTS = testsuite
 
 testsuite_SOURCES = testsuite.cpp \
-    unit/matrix.cpp unit/half.cpp unit/trig.cpp unit/build.cpp
+    unit/matrix.cpp unit/half.cpp unit/trig.cpp unit/build.cpp unit/real.cpp
 testsuite_CPPFLAGS = @LOL_CFLAGS@ @PIPI_CFLAGS@
 testsuite_LDFLAGS = $(top_builddir)/src/liblol.a @LOL_LIBS@ @PIPI_LIBS@
 testsuite_DEPENDENCIES = $(top_builddir)/src/liblol.a