Get rid of NULLs in core/

core/fxcodec/codec/fx_codec_png.cpp

Index: core/fxcodec/codec/fx_codec_png.cpp
diff --git a/core/fxcodec/codec/fx_codec_png.cpp b/core/fxcodec/codec/fx_codec_png.cpp
index 61d4cebdbba28aa3ab2fc363232b848e75c51fc0..0808b26620268829bf12f1d758ea8273000609aa 100644
--- a/core/fxcodec/codec/fx_codec_png.cpp
+++ b/core/fxcodec/codec/fx_codec_png.cpp
@@ -110,13 +110,13 @@ static void _png_free_func(void* p) {
 };
 static void _png_get_header_func(png_structp png_ptr, png_infop info_ptr) {
   FXPNG_Context* p = (FXPNG_Context*)png_get_progressive_ptr(png_ptr);
-  if (p == NULL) {
+  if (!p)
     return;
-  }
+
   CCodec_PngModule* pModule = (CCodec_PngModule*)p->parent_ptr;
-  if (pModule == NULL) {
+  if (!pModule)
     return;
-  }
+
   png_uint_32 width = 0, height = 0;
   int bpc = 0, color_type = 0, color_type1 = 0, pass = 0;
   double gamma = 1.0;
@@ -182,9 +182,9 @@ static void _png_get_row_func(png_structp png_ptr,
                               png_uint_32 row_num,
                               int pass) {
   FXPNG_Context* p = (FXPNG_Context*)png_get_progressive_ptr(png_ptr);
-  if (p == NULL) {
+  if (!p)
     return;
-  }
+
   CCodec_PngModule* pModule = (CCodec_PngModule*)p->parent_ptr;
   uint8_t* src_buf = NULL;
   if (!pModule->AskScanlineBufCallback(p->child_ptr, row_num, src_buf)) {