scripts: Add makefile.emcc for building libpng with Emscripten
Adapt makefile.clang to invoke the Emscripten toolchain utilities.
Co-authored-by: Kirk Roerig <mr.possoms@gmail.com>
Co-authored-by: Cosmin Truta <ctruta@gmail.com>
diff --git a/scripts/makefile.emcc b/scripts/makefile.emcc
new file mode 100644
index 0000000..5d27621
--- /dev/null
+++ b/scripts/makefile.emcc
@@ -0,0 +1,83 @@
+# makefile for libpng using emscripten
+# Copyright (C) 2000, 2014, 2019-2022 Cosmin Truta
+# Copyright (C) 2021 Kirk Roerig
+# Copyright (C) 2008, 2014 Glenn Randers-Pehrson
+# Copyright (C) 1995 Guy Eric Schalnat, Group 42, Inc.
+#
+# This code is released under the libpng license.
+# For conditions of distribution and use, see the disclaimer
+# and license in png.h
+
+# Location of the zlib library and include files
+ZLIBINC = ../zlib
+ZLIBLIB = ../zlib
+
+# Compiler, linker, lib and other tools
+CC = emcc
+LD = $(CC)
+AR_RC = emar rcs
+RANLIB = emranlib
+CP = cp
+RM_F = rm -f
+
+CPPFLAGS = -I$(ZLIBINC) # -DPNG_DEBUG=5
+CFLAGS = -O2 -Wall -Wextra -Wundef
+LDFLAGS = -L$(ZLIBLIB)
+PNGTEST_LDFLAGS = --preload-file=pngtest.png
+LIBS = -lz -lm
+
+# Pre-built configuration
+# See scripts/pnglibconf.mak for more options
+PNGLIBCONF_H_PREBUILT = scripts/pnglibconf.h.prebuilt
+
+# File lists
+OBJS = png.o pngerror.o pngget.o pngmem.o pngpread.o \
+ pngread.o pngrio.o pngrtran.o pngrutil.o pngset.o \
+ pngtrans.o pngwio.o pngwrite.o pngwtran.o pngwutil.o
+
+# Targets
+all: static
+
+pnglibconf.h: $(PNGLIBCONF_H_PREBUILT)
+ $(CP) $(PNGLIBCONF_H_PREBUILT) $@
+
+.c.o:
+ $(CC) -c $(CPPFLAGS) $(CFLAGS) -o $@ $<
+
+static: libpng.a pngtest
+
+shared:
+ @echo This makefile cannot create shared libraries.
+ @false
+
+libpng.a: $(OBJS)
+ $(AR_RC) $@ $(OBJS)
+ $(RANLIB) $@
+
+test: pngtest
+ node ./pngtest
+
+pngtest: pngtest.o libpng.a
+ $(LD) $(LDFLAGS) $(PNGTEST_LDFLAGS) -o $@ pngtest.o libpng.a $(LIBS)
+
+clean:
+ $(RM_F) *.o libpng.a pngtest pngout.png pnglibconf.h
+ $(RM_F) pngtest.data pngtest.wasm
+
+png.o: png.h pngconf.h pnglibconf.h pngpriv.h pngstruct.h pnginfo.h pngdebug.h
+pngerror.o: png.h pngconf.h pnglibconf.h pngpriv.h pngstruct.h pnginfo.h pngdebug.h
+pngget.o: png.h pngconf.h pnglibconf.h pngpriv.h pngstruct.h pnginfo.h pngdebug.h
+pngmem.o: png.h pngconf.h pnglibconf.h pngpriv.h pngstruct.h pnginfo.h pngdebug.h
+pngpread.o: png.h pngconf.h pnglibconf.h pngpriv.h pngstruct.h pnginfo.h pngdebug.h
+pngread.o: png.h pngconf.h pnglibconf.h pngpriv.h pngstruct.h pnginfo.h pngdebug.h
+pngrio.o: png.h pngconf.h pnglibconf.h pngpriv.h pngstruct.h pnginfo.h pngdebug.h
+pngrtran.o: png.h pngconf.h pnglibconf.h pngpriv.h pngstruct.h pnginfo.h pngdebug.h
+pngrutil.o: png.h pngconf.h pnglibconf.h pngpriv.h pngstruct.h pnginfo.h pngdebug.h
+pngset.o: png.h pngconf.h pnglibconf.h pngpriv.h pngstruct.h pnginfo.h pngdebug.h
+pngtrans.o: png.h pngconf.h pnglibconf.h pngpriv.h pngstruct.h pnginfo.h pngdebug.h
+pngwio.o: png.h pngconf.h pnglibconf.h pngpriv.h pngstruct.h pnginfo.h pngdebug.h
+pngwrite.o: png.h pngconf.h pnglibconf.h pngpriv.h pngstruct.h pnginfo.h pngdebug.h
+pngwtran.o: png.h pngconf.h pnglibconf.h pngpriv.h pngstruct.h pnginfo.h pngdebug.h
+pngwutil.o: png.h pngconf.h pnglibconf.h pngpriv.h pngstruct.h pnginfo.h pngdebug.h
+
+pngtest.o: png.h pngconf.h pnglibconf.h
