Yocto Multifile compilation - linux

Question

I have 4 files in different directories.
1. /home/Linux/NXP/XYZ/Embedded/Read/read.c
2. /home/Linux/NXP/XYZ/Embedded/main/mainfun.c
3. /home/Linux/NXP/XYZ/Embedded/write/write.c
4. /home/Linux/NXP/XYZ/Embedded/config/config.c
and the .bb file is located at
"/home/Linux/NXP/yocto/jethro/yocto/source/meta-mylayer/recipes-app/mainfun/mainfun.bb"
From mainfun.c I am calling different functions, the definitions of which are present inside write.c, config.c, read.c.
I have only come across a single file compilation using yocto so can you please help how do I write the .bb file? How can I compile and generate "XYZ_app" executable?
Here I attached my .bb file which I have written but it's not working:
DESCRIPTION = "multiple file compilation"
PR = "r0"
LICENSE = "CLOSED"
SRC_URI += "file://home/Linux/NXP/XYZ/Embedded/ \
"
S = "${WORKDIR}"
do_compile() {
${CC} ${CFLAGS} ${LDFLAGS} --static -c ${WORKDIR}}/home/Linux/NXP/XYZ/Embedded/read/read.c
${CC} ${CFLAGS} ${LDFLAGS} --static -c ${WORKDIR}}/home/Linux/NXP/XYZ/Embedded/write/write.c
${CC} ${CFLAGS} ${LDFLAGS} --static -c ${WORKDIR}}/home/Linux/NXP/XYZ/Embedded/conf/conf.c
${CC} ${CFLAGS} ${LDFLAGS} --static -c ${WORKDIR}}/home/Linux/NXP/XYZ/Embedded/mainfun/mainfun.c
${CC} ${CFLAGS} ${LDFLAGS} --static ${WORKDIR} /home/Linux/NXP/XYZ/Embedded/Read/read.o /home/Linux/NXP/XYZ/Embedded/write/write.o /home/Linux/NXP/XYZ/Embedded/conf/conf.o /home/Linux/NXP/XYZ/Embedded/mainfun/mainfun.o -c XYZ_App
}
do_install() {
install -m 0755 -d ${D}${bindir}
install -m 0755 ${S}/XYZ_App ${D}${bindir}
}

Answer 1

The direct compilation of source files in a recipe is a testing/emergency solution at best. Whenever it comes to something even only slightly advanced, the correct way is to use a build system of any kind.
Those directly supported in OpenEmbedded include (amongst others)
Makefiles
Autotools
CMake
Here are examples for a couple of recipes for those systems: http://www.yoctoproject.org/docs/2.4/dev-manual/dev-manual.html#new-recipe-testing-examples
Properly packing the sources up also gives you a way to easily test the compilation and application without having to invoke the whole bitbake process. All of them have pros and cons, so you might want to dig a deep further. For a start into autotools, this seems to be a good thing:
https://developer.gnome.org/anjuta-build-tutorial/stable/create-autotools.html.en
An alternative is to look at GNU hello, and also the corresponding recipe.