compile streamvbyte as C, not C++ (#634)

CMakeLists.txt

@@ -61,7 +61,7 @@ endif()
 if(MSVC)
  	find_package(unofficial-sqlite3 CONFIG REQUIRED)
 	add_library(SQLite::SQLite3 ALIAS unofficial::sqlite3::sqlite3)
-	add_definitions(-D_USE_MATH_DEFINES -DWIN32_LEAN_AND_MEAN -DNOGDI)
+	add_definitions(-D_USE_MATH_DEFINES -DWIN32_LEAN_AND_MEAN -DNOGDI -D__restrict__=__restrict)
   	set(THREAD_LIB "")
 else()
 	find_package(SQLite3 REQUIRED)
@@ -72,9 +72,9 @@ file(GLOB tilemaker_src_files
 	src/attribute_store.cpp
 	src/coordinates.cpp
 	src/coordinates_geom.cpp
-	src/external/streamvbyte_decode.cc
-	src/external/streamvbyte_encode.cc
-	src/external/streamvbyte_zigzag.cc
+	src/external/streamvbyte_decode.c
+	src/external/streamvbyte_encode.c
+	src/external/streamvbyte_zigzag.c
 	src/geojson_processor.cpp
 	src/geom.cpp
 	src/helpers.cpp

Makefile

@@ -84,6 +84,7 @@ prefix = /usr/local
 MANPREFIX := /usr/share/man
 TM_VERSION ?= $(shell git describe --tags --abbrev=0)
 CXXFLAGS ?= -O3 -Wall -Wno-unknown-pragmas -Wno-sign-compare -std=c++14 -pthread -fPIE -DTM_VERSION=$(TM_VERSION) $(CONFIG)
+CFLAGS ?= -O3 -Wall -Wno-unknown-pragmas -Wno-sign-compare -std=c99 -fPIE -DTM_VERSION=$(TM_VERSION) $(CONFIG)
 LIB := -L$(PLATFORM_PATH)/lib -lz $(LUA_LIBS) -lboost_program_options -lsqlite3 -lboost_filesystem -lboost_system -lboost_iostreams -lshp -pthread
 INC := -I$(PLATFORM_PATH)/include -isystem ./include -I./src $(LUA_CFLAGS)
 
@@ -194,8 +195,8 @@ server: \
 %.o: %.cpp
 	$(CXX) $(CXXFLAGS) -o $@ -c $< $(INC)
 
-%.o: %.cc
-	$(CXX) $(CXXFLAGS) -o $@ -c $< $(INC)
+%.o: %.c
+	$(CC) $(CFLAGS) -o $@ -c $< $(INC)
 
 install:
 	install -m 0755 -d $(DESTDIR)$(prefix)/bin/

src/external/streamvbyte_encode.cc → src/external/streamvbyte_encode.c

@@ -11,7 +11,7 @@
 #include "streamvbyte_x64_encode.c"
 #endif
 
-static uint8_t svb_encode_data(uint32_t val, uint8_t * *dataPtrPtr) {
+static uint8_t svb_encode_data(uint32_t val, uint8_t *__restrict__ *dataPtrPtr) {
   uint8_t *dataPtr = *dataPtrPtr;
   uint8_t code;
 
@@ -37,8 +37,8 @@ static uint8_t svb_encode_data(uint32_t val, uint8_t * *dataPtrPtr) {
 }
 
 static uint8_t *svb_encode_scalar(const uint32_t *in,
-                                  uint8_t * keyPtr,
-                                  uint8_t * dataPtr,
+                                  uint8_t *__restrict__ keyPtr,
+                                  uint8_t *__restrict__ dataPtr,
                                   uint32_t count) {
   if (count == 0)
     return dataPtr; // exit immediately if no data

src/external/streamvbyte_x64_decode.c

@@ -8,7 +8,7 @@
 #ifdef STREAMVBYTE_X64
 STREAMVBYTE_TARGET_SSE41
 static inline __m128i svb_decode_sse41(uint32_t key,
-                                  const uint8_t * *dataPtrPtr) {
+                                  const uint8_t *__restrict__ *dataPtrPtr) {
   uint8_t len;
   __m128i Data = _mm_loadu_si128((const __m128i *)*dataPtrPtr);
   uint8_t *pshuf = (uint8_t *) &shuffleTable[key];
@@ -37,8 +37,8 @@ STREAMVBYTE_UNTARGET_REGION
 
 STREAMVBYTE_TARGET_SSE41
 static inline const uint8_t *svb_decode_sse41_simple(uint32_t *out,
-                                     const uint8_t * keyPtr,
-                                     const uint8_t * dataPtr,
+                                     const uint8_t *__restrict__ keyPtr,
+                                     const uint8_t *__restrict__ dataPtr,
                                      uint64_t count) {
 
   uint64_t keybytes = count / 4; // number of key bytes

src/external/streamvbyte_x64_encode.c

@@ -54,11 +54,8 @@ STREAMVBYTE_UNTARGET_REGION
 STREAMVBYTE_TARGET_SSE41
 static size_t streamvbyte_encode_SSE41 (const uint32_t* in, uint32_t count, uint8_t* out) {
 	uint32_t keyLen = (count >> 2) + (((count & 3) + 3) >> 2); // 2-bits per each rounded up to byte boundary
-// cldellow: NB `restrict` is only available in C99, not c++14.
-//	uint8_t *restrict keyPtr = &out[0];
-//	uint8_t *restrict dataPtr = &out[keyLen]; // variable length data after keys
-	uint8_t * keyPtr = &out[0];
-	uint8_t * dataPtr = &out[keyLen]; // variable length data after keys
+	uint8_t *restrict keyPtr = &out[0];
+	uint8_t *restrict dataPtr = &out[keyLen]; // variable length data after keys
 
 	for (const uint32_t* end = &in[(count & ~7U)]; in != end; in += 8)
 	{