gnu: Add FXDiv.

* gnu/packages/maths.scm (fxdiv): New variable.
* gnu/packages/patches/fxdiv-system-libraries.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.

gnu/local.mk

@@ -1032,6 +1032,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/freedink-engine-fix-sdl-hints.patch	\
   %D%/packages/patches/freeimage-unbundle.patch		\
   %D%/packages/patches/fuse-overlapping-headers.patch				\
+  %D%/packages/patches/fxdiv-system-libraries.patch		\
   %D%/packages/patches/gajim-honour-GAJIM_PLUGIN_PATH.patch	\
   %D%/packages/patches/ganeti-deterministic-manual.patch	\
   %D%/packages/patches/ganeti-disable-version-symlinks.patch	\

gnu/packages/maths.scm

@@ -127,6 +127,7 @@
   #:use-module (gnu packages netpbm)
   #:use-module (gnu packages ocaml)
   #:use-module (gnu packages onc-rpc)
+  #:use-module (gnu packages parallel)
   #:use-module (gnu packages pcre)
   #:use-module (gnu packages popt)
   #:use-module (gnu packages perl)
@@ -6657,3 +6658,33 @@ high-performance multidimensional array containers for scientific computing.")
     (license (list license:artistic2.0
                    license:bsd-3
                    license:lgpl3+))))
+
+(define-public fxdiv
+  ;; There is currently no tag in this repo.
+  (let ((commit "63058eff77e11aa15bf531df5dd34395ec3017c8")
+        (version "0.0")
+        (revision "1"))
+    (package
+      (name "fxdiv")
+      (version (git-version version revision commit))
+      (home-page "https://github.com/Maratyszcza/FXdiv")
+      (source (origin
+                (method git-fetch)
+                (uri (git-reference (url home-page) (commit commit)))
+                (file-name (git-file-name name version))
+                (sha256
+                 (base32
+                  "0zwzh8gmbx4m6b18s5nf13b0dk5yjkd1fs8f421bl7fz5f9gjd9f"))
+                (patches (search-patches "fxdiv-system-libraries.patch"))))
+      (build-system cmake-build-system)
+      (inputs
+       `(("googletest" ,googletest)
+         ("googlebenchmark" ,googlebenchmark)))
+      (synopsis
+       "C++ library for division via fixed-point multiplication by inverse")
+      (description
+       "On modern CPUs and GPUs, integer division is several times slower than
+multiplication.  FXdiv implements an algorithm to replace an integer division
+with a multiplication and two shifts.  This algorithm improves performance
+when an application performs repeated divisions by the same divisor.")
+      (license license:expat))))

gnu/packages/patches/fxdiv-system-libraries.patch

@@ -0,0 +1,44 @@
+This patch allows the build process to use the provided dependencies instead
+of adding their source as CMake sub-directories (in which case "make install"
+would install googletest's and googlebenchmark's libraries and headers).
+
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index bcae6b5..ff6710d 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -21,7 +21,7 @@ IF(FXDIV_BUILD_TESTS)
+ ENDIF()
+ 
+ # ---[ Download deps
+-IF(FXDIV_BUILD_TESTS AND NOT DEFINED GOOGLETEST_SOURCE_DIR)
++IF(FALSE)
+   MESSAGE(STATUS "Downloading Google Test to ${CMAKE_BINARY_DIR}/googletest-source (define GOOGLETEST_SOURCE_DIR to avoid it)")
+   CONFIGURE_FILE(cmake/DownloadGoogleTest.cmake "${CMAKE_BINARY_DIR}/googletest-download/CMakeLists.txt")
+   EXECUTE_PROCESS(COMMAND "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" .
+@@ -31,7 +31,7 @@ IF(FXDIV_BUILD_TESTS AND NOT DEFINED GOOGLETEST_SOURCE_DIR)
+   SET(GOOGLETEST_SOURCE_DIR "${CMAKE_BINARY_DIR}/googletest-source" CACHE STRING "Google Test source directory")
+ ENDIF()
+ 
+-IF(FXDIV_BUILD_BENCHMARKS AND NOT DEFINED GOOGLEBENCHMARK_SOURCE_DIR)
++IF(FALSE)
+   MESSAGE(STATUS "Downloading Google Benchmark to ${CMAKE_BINARY_DIR}/googlebenchmark-source (define GOOGLEBENCHMARK_SOURCE_DIR to avoid it)")
+   CONFIGURE_FILE(cmake/DownloadGoogleBenchmark.cmake "${CMAKE_BINARY_DIR}/googlebenchmark-download/CMakeLists.txt")
+   EXECUTE_PROCESS(COMMAND "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" .
+@@ -54,7 +54,7 @@ INSTALL(FILES include/fxdiv.h DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+ 
+ IF(FXDIV_BUILD_TESTS)
+   # ---[ Build google test
+-  IF(NOT TARGET gtest)
++  IF(FALSE)
+     SET(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
+     ADD_SUBDIRECTORY(
+       "${GOOGLETEST_SOURCE_DIR}"
+@@ -78,7 +78,7 @@ ENDIF()
+ 
+ IF(FXDIV_BUILD_BENCHMARKS)
+   # ---[ Build google benchmark
+-  IF(NOT TARGET benchmark)
++  IF(FALSE)
+     SET(BENCHMARK_ENABLE_TESTING OFF CACHE BOOL "" FORCE)
+     ADD_SUBDIRECTORY(
+       "${GOOGLEBENCHMARK_SOURCE_DIR}"