feat: Adding AVX implementation for mixing audio. (#745)

Co-authored-by: Brain <[email protected]>

cmake/DetectArchitecture.cmake

@@ -0,0 +1,56 @@
+include(CheckCXXSourceRuns)
+
+function(check_instruction_set INSTRUCTION_SET_NAME INSTRUCTION_SET_FLAG INSTRUCTION_SET_INTRINSIC)
+
+    set(INSTRUCTION_SET_CODE "
+        #include <immintrin.h>
+        #include <stdint.h>
+        int main()
+        {
+            ${INSTRUCTION_SET_INTRINSIC};
+            return 0;
+        }
+    ")
+
+    set(CMAKE_REQUIRED_FLAGS "${INSTRUCTION_SET_FLAG}")
+    CHECK_CXX_SOURCE_RUNS("${INSTRUCTION_SET_CODE}" "${INSTRUCTION_SET_NAME}")
+    if(${INSTRUCTION_SET_NAME})
+        set(AVX_TYPE "${INSTRUCTION_SET_NAME}" PARENT_SCOPE)
+        set(AVX_FLAG "${INSTRUCTION_SET_FLAG}" PARENT_SCOPE)
+        set(AVX_NAME "${INSTRUCTION_SET_NAME}" PARENT_SCOPE)
+    else()
+        message(STATUS "Instruction set ${INSTRUCTION_SET_NAME} not supported. Falling back to the previous instruction set.")
+        return()
+    endif()
+endfunction()
+
+if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+    set(INSTRUCTION_SETS
+        "T_AVX?/arch:AVX?auto result = _mm_testz_ps(__m128{}, __m128{})"
+        "T_AVX2?/arch:AVX2?auto result = _mm256_extract_epi64(__m256i{}, 0)"
+        "T_AVX512?/arch:AVX512?auto result = _mm512_add_ps(__m512i{}, __m512i{}).auto result2 = _mm512_cmplt_epu8_mask(__m512i{}, __m512i{})"
+    )
+else()
+    set(INSTRUCTION_SETS
+        "T_AVX?-mavx.-mpclmul.-mbmi?auto result = _mm_testz_ps(__m128{}, __m128{})"
+        "T_AVX2?-mavx2.-mavx.-mpclmul.-mbmi?auto result = _mm256_extract_epi64(__m256i{}, 0)"
+        "T_AVX512?-mavx512bw.-mavx512f.-mavx2.-mavx.-mpclmul.-mbmi?auto result = _mm512_add_ps(__m512i{}, __m512i{}).auto result2 = _mm512_cmplt_epu8_mask(__m512i{}, __m512i{})"
+    )
+endif()
+
+set(CMAKE_REQUIRED_FLAGS_SAVE "${CMAKE_REQUIRED_FLAGS}")
+
+set(AVX_NAME "T_Fallback")
+
+foreach(INSTRUCTION_SET IN LISTS INSTRUCTION_SETS)
+    string(REPLACE "?" ";" CURRENT_LIST "${INSTRUCTION_SET}")
+    list(GET CURRENT_LIST 0 INSTRUCTION_SET_NAME)
+    list(GET CURRENT_LIST 1 INSTRUCTION_SET_FLAG)
+    string(REPLACE "." ";" INSTRUCTION_SET_FLAG "${INSTRUCTION_SET_FLAG}")
+    list(GET CURRENT_LIST 2 INSTRUCTION_SET_INTRINSIC)
+    string(REPLACE "." ";" INSTRUCTION_SET_INTRINSIC "${INSTRUCTION_SET_INTRINSIC}")
+    check_instruction_set("${INSTRUCTION_SET_NAME}" "${INSTRUCTION_SET_FLAG}" "${INSTRUCTION_SET_INTRINSIC}")
+endforeach()
+
+message(STATUS "Detected CPU Architecture: ${AVX_NAME}")
+set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS_SAVE}")

cmake/LINUXx86ToolChain.cmake

@@ -22,6 +22,7 @@ SET(OPENSSL_SSL_LIBRARY /usr/lib/i386-linux-gnu/libssl.so)
 
 SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -m32 " CACHE INTERNAL "" FORCE)
 SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -m32 " CACHE INTERNAL "" FORCE)
+set(T_AVX_EXITCODE "0" CACHE STRING INTERNAL FORCE)
 
 EXECUTE_PROCESS(COMMAND sudo dpkg --add-architecture i386)
 EXECUTE_PROCESS(COMMAND sudo apt-get update)

include/dpp/discordvoiceclient.h

@@ -37,6 +37,7 @@
 #include <dpp/dispatcher.h>
 #include <dpp/cluster.h>
 #include <dpp/discordevents.h>
+#include <dpp/isa_detection.h>
 #include <dpp/socket.h>
 #include <queue>
 #include <thread>
@@ -58,6 +59,23 @@ namespace dpp {
 
 using json = nlohmann::json;
 
+/*
+* @brief For holding a moving average of the number of current voice users, for applying a smooth gain ramp.
+*/
+struct DPP_EXPORT moving_averager {
+	moving_averager() = default;
+
+	moving_averager(uint64_t collection_count_new);
+
+	moving_averager operator+=(int64_t value);
+
+	operator float();
+
+protected:
+	std::deque<int64_t> values{};
+	uint64_t collectionCount{};
+};
+
 // Forward declaration
 class cluster;
 
@@ -473,6 +491,21 @@ class DPP_EXPORT discord_voice_client : public websocket_client
 	 */
 	bool terminating;
 
+	/**
+	 * @brief The gain value for the end of the current voice iteration.
+	 */
+	float end_gain;
+
+	/**
+	 * @brief The gain value for the current voice iteration.
+	 */
+	float current_gain;
+
+	/**
+	 * @brief The amount to increment each successive sample for, for the current voice iteration.
+	 */
+	float increment;
+
 	/**
 	 * @brief Heartbeat interval for sending heartbeat keepalive
 	 */
@@ -503,6 +536,11 @@ class DPP_EXPORT discord_voice_client : public websocket_client
 	 */
 	snowflake server_id;
 
+	/**
+	 * @brief Moving averager.
+	 */
+	moving_averager moving_average;
+
 	/**
 	 * @brief Channel ID
 	 */