From b7df26037b869d4989890801ee2da1c634d8b33d Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <icculus@icculus.org>
Date: Thu, 24 Oct 2019 23:17:19 -0400
Subject: [PATCH] cmake: added support for enabling the ARM SIMD/NEON code.

---
 CMakeLists.txt             | 75 ++++++++++++++++++++++++++++++++++++++
 include/SDL_config.h.cmake |  2 +
 2 files changed, 77 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index b1c3eba04..7e8591d77 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -329,6 +329,8 @@ set_option(SSE                 "Use SSE assembly routines" ${OPT_DEF_ASM})
 set_option(SSE2                "Use SSE2 assembly routines" ${OPT_DEF_SSEMATH})
 set_option(SSE3                "Use SSE3 assembly routines" ${OPT_DEF_SSEMATH})
 set_option(ALTIVEC             "Use Altivec assembly routines" ${OPT_DEF_ASM})
+set_option(ARMSIMD             "use SIMD assembly blitters on ARM" ON)
+set_option(ARMNEON             "use NEON assembly blitters on ARM" ON)
 set_option(DISKAUDIO           "Support the disk writer audio driver" ON)
 set_option(DUMMYAUDIO          "Support the dummy audio driver" ON)
 set_option(VIDEO_DIRECTFB      "Use DirectFB video driver" OFF)
@@ -671,6 +673,61 @@ if(ASSEMBLY)
         endif()
       endif()
     endif()
+
+    if(ARMSIMD)
+      set(ORIG_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
+      set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -x assembler-with-cpp")
+      check_c_source_compiles("
+        .text
+        .arch armv6
+        .object_arch armv4
+        .arm
+        .altmacro
+        #ifndef __ARM_EABI__
+        #error EABI is required (to be sure that calling conventions are compatible)
+        #endif
+        pld [r0]
+        uqadd8 r0, r0, r0
+      " ARMSIMD_FOUND)
+      set(CMAKE_REQUIRED_FLAGS "${ORIG_CMAKE_REQUIRED_FLAGS}")
+
+      if(ARMSIMD_FOUND)
+        set(HAVE_ARMSIMD TRUE)
+        set(SDL_ARM_SIMD_BLITTERS 1)
+        file(GLOB ARMSIMD_SOURCES ${SDL2_SOURCE_DIR}/src/video/arm/pixman-arm-simd*.S)
+        set(SOURCE_FILES ${SOURCE_FILES} ${ARMSIMD_SOURCES})
+        set(WARN_ABOUT_ARM_SIMD_ASM_MIT TRUE)
+      endif()
+    endif()
+
+    if(ARMNEON)
+      set(ORIG_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
+      set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -x assembler-with-cpp")
+      check_c_source_compiles("
+        .text
+        .fpu neon
+        .arch armv7a
+        .object_arch armv4
+        .eabi_attribute 10, 0
+        .arm
+        .altmacro
+        #ifndef __ARM_EABI__
+        #error EABI is required (to be sure that calling conventions are compatible)
+        #endif
+        pld [r0]
+        vmovn.u16 d0, q0
+      " ARMNEON_FOUND)
+      set(CMAKE_REQUIRED_FLAGS "${ORIG_CMAKE_REQUIRED_FLAGS}")
+
+      if(ARMNEON_FOUND)
+        set(HAVE_ARMNEON TRUE)
+        set(SDL_ARM_NEON_BLITTERS 1)
+        file(GLOB ARMNEON_SOURCES ${SDL2_SOURCE_DIR}/src/video/arm/pixman-arm-neon*.S)
+        set(SOURCE_FILES ${SOURCE_FILES} ${ARMNEON_SOURCES})
+        set(WARN_ABOUT_ARM_NEON_ASM_MIT TRUE)
+      endif()
+    endif()
+
   elseif(MSVC_VERSION GREATER 1500)
     # TODO: SDL_cpuinfo.h needs to support the user's configuration wish
     # for MSVC - right now it is always activated
@@ -1927,6 +1984,24 @@ if(UNIX)
   message(STATUS "")
 endif()
 
+if(WARN_ABOUT_ARM_SIMD_ASM_MIT)
+  message(STATUS "")
+  message(STATUS "SDL is being built with ARM SIMD optimizations, which")
+  message(STATUS "uses code licensed under the MIT license. If this is a")
+  message(STATUS "problem, please disable that code by rerunning CMake with:")
+  message(STATUS "")
+  message(STATUS "    -DARMSIMD=OFF")
+endif()
+
+if(WARN_ABOUT_ARM_NEON_ASM_MIT)
+  message(STATUS "")
+  message(STATUS "SDL is being built with ARM NEON optimizations, which")
+  message(STATUS "uses code licensed under the MIT license. If this is a")
+  message(STATUS "problem, please disable that code by rerunning CMake with:")
+  message(STATUS "")
+  message(STATUS "    -DARMNEON=OFF")
+endif()
+
 # Ensure that the extra cflags are used at compile time
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${EXTRA_CFLAGS}")
 
diff --git a/include/SDL_config.h.cmake b/include/SDL_config.h.cmake
index e791aef4a..34220f3ff 100644
--- a/include/SDL_config.h.cmake
+++ b/include/SDL_config.h.cmake
@@ -415,6 +415,8 @@
 /* Enable assembly routines */
 #cmakedefine SDL_ASSEMBLY_ROUTINES @SDL_ASSEMBLY_ROUTINES@
 #cmakedefine SDL_ALTIVEC_BLITTERS @SDL_ALTIVEC_BLITTERS@
+#cmakedefine SDL_ARM_SIMD_BLITTERS @SDL_ARM_SIMD_BLITTERS@
+#cmakedefine SDL_ARM_NEON_BLITTERS @SDL_ARM_NEON_BLITTERS@
 
 /* Enable dynamic libsamplerate support */
 #cmakedefine SDL_LIBSAMPLERATE_DYNAMIC @SDL_LIBSAMPLERATE_DYNAMIC@