[Buildroot] [PATCH v5 23/32] xbmc: fix arm/uclibc compilation

[Bernd Kuhls <bernd.kuhls@t-online.de>]

xbmc-0002-mathutil.patch: Fix arm compilation bug, fetched from upstream PR:
                          https://github.com/xbmc/xbmc/pull/3760

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
---
 package/xbmc/Config.in                |    6 +-
 package/xbmc/xbmc-0002-mathutil.patch |  213 +++++++++++++++++++++++++++++++++
 2 files changed, 216 insertions(+), 3 deletions(-)
 create mode 100644 package/xbmc/xbmc-0002-mathutil.patch

diff --git a/package/xbmc/Config.in b/package/xbmc/Config.in
index 9ca7620..d592ad6 100644
--- a/package/xbmc/Config.in
+++ b/package/xbmc/Config.in
@@ -1,9 +1,9 @@
 comment "xbmc needs a toolchain w/ C++, largefile, threads, wchar"
-	depends on BR2_i386 || BR2_x86_64
+	depends on BR2_arm || BR2_i386 || BR2_x86_64
 	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_LARGEFILE || !BR2_TOOLCHAIN_HAS_THREADS || !BR2_USE_WCHAR
 
 comment "xbmc requires an OpenGL ES and EGL backend"
-	depends on BR2_i386 || BR2_x86_64
+	depends on BR2_arm || BR2_i386 || BR2_x86_64
 	depends on !BR2_PACKAGE_HAS_LIBEGL || !BR2_PACKAGE_HAS_LIBGLES
 
 menuconfig BR2_PACKAGE_XBMC
@@ -62,7 +62,7 @@ menuconfig BR2_PACKAGE_XBMC
 	depends on BR2_PACKAGE_HAS_LIBEGL && BR2_PACKAGE_HAS_LIBGLES
 	depends on BR2_USE_MMU # python
 	depends on BR2_USE_WCHAR
-	depends on BR2_i386 || BR2_x86_64
+	depends on BR2_arm || BR2_i386 || BR2_x86_64
 	help
 	  XBMC is an award-winning free and open source (GPL) software
 	  media player and entertainment hub for digital media.
diff --git a/package/xbmc/xbmc-0002-mathutil.patch b/package/xbmc/xbmc-0002-mathutil.patch
new file mode 100644
index 0000000..33f91eb
--- /dev/null
+++ b/package/xbmc/xbmc-0002-mathutil.patch
@@ -0,0 +1,213 @@
+Taken from upstream PR: https://github.com/xbmc/xbmc/pull/3760
+
+Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
+
+
+From 7388e8be7cd5e78100532ebf0dba15dccb7b03f8 Mon Sep 17 00:00:00 2001
+From: Ben Avison <bavison@riscosopen.org>
+Date: Tue, 3 Dec 2013 15:51:39 +0000
+Subject: [PATCH] Faster and simpler portable implementation of
+ MathUtils::round_int().
+
+Much as I like a bit of inline assembler, I have also removed the ARM versions
+of MathUtils::truncate_int() and MathUtils::round_int(). The former was just
+how any sane compiler should have assembled a cast from double to signed int
+anyway. The latter was a much too complicated way to achieve the desired
+effect, and was switched out in most ARM builds anyway in favour of the old
+portable implementation that used floor().
+
+Verified that MathUtils::test() still passes, and that GCC is now able to
+inline MathUtils::round_int(), where it didn't previously.
+
+I tested on a Raspberry Pi with the default theme, displaying the front page
+with the RSS ticker enabled. This saturates the CPU, so I'm measuring the
+improvement using the debug window's FPS figure. This patch improves this from
+~50.8 FPS to ~52.6 FPS.
+---
+ xbmc/utils/MathUtils.h | 129 +++++++++++++++++++++++--------------------------
+ 1 file changed, 61 insertions(+), 68 deletions(-)
+
+diff --git a/xbmc/utils/MathUtils.h b/xbmc/utils/MathUtils.h
+index 96af9f4..0dae77d 100644
+--- a/xbmc/utils/MathUtils.h
++++ b/xbmc/utils/MathUtils.h
+@@ -34,17 +34,13 @@
+ 
+ #if defined(__ppc__) || \
+     defined(__powerpc__) || \
+-   (defined(TARGET_DARWIN_IOS) && defined(__llvm__)) || \
+-   (defined(TARGET_ANDROID) && defined(__arm__)) || \
+-    defined(TARGET_RASPBERRY_PI)
++    defined(__arm__)
+   #define DISABLE_MATHUTILS_ASM_ROUND_INT
+ #endif
+ 
+ #if defined(__ppc__) || \
+     defined(__powerpc__) || \
+-   (defined(TARGET_DARWIN) && defined(__llvm__)) || \
+-   (defined(TARGET_ANDROID) && defined(__arm__)) || \
+-    defined(TARGET_RASPBERRY_PI)
++    defined(__arm__)
+   #define DISABLE_MATHUTILS_ASM_TRUNCATE_INT
+ #endif
+ 
+@@ -73,60 +69,63 @@
+   {
+     assert(x > static_cast<double>(INT_MIN / 2) - 1.0);
+     assert(x < static_cast<double>(INT_MAX / 2) + 1.0);
+-    const float round_to_nearest = 0.5f;
+-    int i;
+ 
+ #if defined(DISABLE_MATHUTILS_ASM_ROUND_INT)
+-    i = floor(x + round_to_nearest);
+-
+-#elif defined(__arm__)
+-    // From 'ARM-v7-M Architecture Reference Manual' page A7-569:
+-    //  "The floating-point to integer operation (vcvt) [normally] uses the Round towards Zero rounding mode"
+-    // Because of this...we must use some less-than-straightforward logic to perform this operation without
+-    //  changing the rounding mode flags
+-
+-    /* The assembly below implements the following logic:
+-     if (x < 0)
+-       inc = -0.5f
+-     else
+-       inc = 0.5f
+-     int_val = trunc(x+inc);
+-     err = x - int_val;
+-     if (err == 0.5f)
+-       int_val++;
+-     return int_val;
+-    */
++    /* This implementation warrants some further explanation.
++     *
++     * First, a couple of notes on rounding:
++     * 1) C casts from float/double to integer round towards zero.
++     * 2) Float/double additions are rounded according to the normal rules,
++     *    in other words: on some architectures, it's fixed at compile-time,
++     *    and on others it can be set using fesetround()). The following
++     *    analysis assumes round-to-nearest with ties rounding to even. This
++     *    is a fairly sensible choice, and is the default with ARM VFP.
++     *
++     * What this function wants is round-to-nearest with ties rounding to
++     * +infinity. This isn't an IEEE rounding mode, even if we could guarantee
++     * that all architectures supported fesetround(), which they don't. Instead,
++     * this adds an offset of 2147483648.5 (= 0x80000000.8p0), then casts to
++     * an unsigned int (crucially, all possible inputs are now in a range where
++     * round to zero acts the same as round to -infinity) and then subtracts
++     * 0x80000000 in the integer domain. The 0.5 component of the offset
++     * converts what is effectively a round down into a round to nearest, with
++     * ties rounding up, as desired.
++     *
++     * There is a catch, that because there is a double rounding, there is a
++     * small region where the input falls just *below* a tie, where the addition
++     * of the offset causes a round *up* to an exact integer, due to the finite
++     * level of precision available in floating point. You need to be aware of
++     * this when calling this function, although@present it is not believed
++     * that XBMC ever attempts to round numbers in this window.
++     *
++     * It is worth proving the size of the affected window. Recall that double
++     * precision employs a mantissa of 52 bits.
++     * 1) For all inputs -0.5 <= x <= INT_MAX
++     *    Once the offset is applied, the most significant binary digit in the
++     *    floating-point representation is +2^31.
++     *    At this magnitude, the smallest step representable in double precision
++     *    is 2^31 / 2^52 = 0.000000476837158203125
++     *    So the size of the range which is rounded up due to the addition is
++     *    half the size of this step, or 0.0000002384185791015625
++     *
++     * 2) For all inputs INT_MIN/2 < x < -0.5
++     *    Once the offset is applied, the most significant binary digit in the
++     *    floating-point representation is +2^30.
++     *    At this magnitude, the smallest step representable in double precision
++     *    is 2^30 / 2^52 = 0.0000002384185791015625
++     *    So the size of the range which is rounded up due to the addition is
++     *    half the size of this step, or 0.00000011920928955078125
++     *
++     * 3) For all inputs INT_MIN <= x <= INT_MIN/2
++     *    The representation once the offset is applied has equal or greater
++     *    precision than the input, so the addition does not cause rounding.
++     */
++    return ((unsigned int) (x + 0x80000000.8p0)) - 0x80000000;
+ 
+-    __asm__ __volatile__ (
+-#if defined(__ARM_PCS_VFP)
+-      "fconstd d1,#%G[rnd_val]     \n\t" // Copy round_to_nearest into a working register (d1 = 0.5)
+ #else
+-      "vmov.F64 d1,%[rnd_val]      \n\t"
+-#endif
+-      "fcmpezd %P[value]           \n\t" // Check value against zero (value == 0?)
+-      "fmstat                      \n\t" // Copy the floating-point status flags into the general-purpose status flags
+-      "it mi                       \n\t"
+-      "vnegmi.F64 d1, d1           \n\t" // if N-flag is set, negate round_to_nearest (if (value < 0) d1 = -1 * d1)
+-      "vadd.F64 d1,%P[value],d1    \n\t" // Add round_to_nearest to value, store result in working register (d1 += value)
+-      "vcvt.S32.F64 s3,d1          \n\t" // Truncate(round towards zero) (s3 = (int)d1)
+-      "vmov %[result],s3           \n\t" // Store the integer result in a general-purpose register (result = s3)
+-      "vcvt.F64.S32 d1,s3          \n\t" // Convert back to floating-point (d1 = (double)s3)
+-      "vsub.F64 d1,%P[value],d1    \n\t" // Calculate the error (d1 = value - d1)
+-#if defined(__ARM_PCS_VFP)
+-      "fconstd d2,#%G[rnd_val]     \n\t" // d2 = 0.5;
+-#else
+-      "vmov.F64 d2,%[rnd_val]      \n\t"
+-#endif
+-      "fcmped d1, d2               \n\t" // (d1 == 0.5?)
+-      "fmstat                      \n\t" // Copy the floating-point status flags into the general-purpose status flags
+-      "it eq                       \n\t"
+-      "addeq %[result],#1          \n\t" // (if (d1 == d2) result++;)
+-      : [result] "=r"(i)                                  // Outputs
+-      : [rnd_val] "Dv" (round_to_nearest), [value] "w"(x) // Inputs
+-      : "d1", "d2", "s3"                                  // Clobbers
+-    );
+-
+-#elif defined(__SSE2__)
++    const float round_to_nearest = 0.5f;
++    int i;
++#if defined(__SSE2__)
+     const float round_dn_to_nearest = 0.4999999f;
+     i = (x > 0) ? _mm_cvttsd_si32(_mm_set_sd(x + round_to_nearest)) : _mm_cvttsd_si32(_mm_set_sd(x - round_dn_to_nearest));
+ 
+@@ -150,8 +149,8 @@
+     );
+ 
+ #endif
+-
+     return i;
++#endif
+   }
+ 
+   /*! \brief Truncate to nearest integer.
+@@ -165,20 +164,13 @@
+   {
+     assert(x > static_cast<double>(INT_MIN / 2) - 1.0);
+     assert(x < static_cast<double>(INT_MAX / 2) + 1.0);
+-    int i;
+ 
+ #if defined(DISABLE_MATHUTILS_ASM_TRUNCATE_INT)
+-    return i = (int)x;
+-
+-#elif defined(__arm__)
+-    __asm__ __volatile__ (
+-      "vcvt.S32.F64 %[result],%P[value]   \n\t" // Truncate(round towards zero) and store the result
+-      : [result] "=w"(i)                        // Outputs
+-      : [value] "w"(x)                          // Inputs
+-    );
+-    return i;
++    return x;
+ 
+-#elif defined(TARGET_WINDOWS)
++#else
++    int i;
++#if defined(TARGET_WINDOWS)
+     const float round_towards_m_i = -0.5f;
+     __asm
+     {
+@@ -204,6 +196,7 @@
+     if (x < 0)
+       i = -i;
+     return (i);
++#endif
+   }
+ 
+   inline int64_t abs(int64_t a)
+-- 
+1.9.1
+
-- 
1.7.10.4