Added clang support

.drone.yml

@@ -1,14 +1,27 @@
 ---
 kind: pipeline
 type: docker
-name: default
+name: build-gcc
 
 steps:
-- name: build
-  image: ubuntu:20.04
-  commands:
-  - apt update
-  - DEBIAN_FRONTEND=noninteractive apt install -y gcc make
-  - make clean
-  - make
+  - name: build
+    image: ubuntu:20.04
+    commands:
+      - apt update
+      - DEBIAN_FRONTEND=noninteractive apt install -y gcc make
+      - make clean
+      - make CC=gcc CFLAGS="-Wall -Werror -Wno-unknown-warning-option -Wno-packed-bitfield-compat"
+---
+kind: pipeline
+type: docker
+name: build-clang
+
+steps:
+  - name: build
+    image: ubuntu:20.04
+    commands:
+      - apt update
+      - DEBIAN_FRONTEND=noninteractive apt install -y clang make
+      - make clean
+      - make CC=clang CFLAGS="-Wall -Werror -Wno-unknown-warning-option -Wno-packed-bitfield-compat"
 ...

Makefile

@@ -1,11 +1,13 @@
+CC=cc
+CFLAGS=-Wall -Wno-unknown-warning-option -Wno-packed-bitfield-compat
 
 default: fm10k-dump
 
 fm10k-dump.o: fm10k-dump.c
-	gcc -c fm10k-dump.c -o fm10k-dump.o -Wall -Wno-packed-bitfield-compat
+	$(CC) -c fm10k-dump.c -o fm10k-dump.o $(CFLAGS)
 
 fm10k-dump: fm10k-dump.o
-	gcc fm10k-dump.o -o fm10k-dump -Wall
+	$(CC) fm10k-dump.o -o fm10k-dump $(CFLAGS)
 
 clean:
 	-rm -f fm10k-dump

README.md

@@ -3,7 +3,7 @@
 Utility that allows dumping the SPI Flash Non-Volatile Memory of the FM10000 family of cards.
 
 ## Requirements
-* GCC >= 4.4.0
+* GCC >= 4.4.0 or clang
 * make
 * [fm10k kernel module](https://git.gammaspectra.live/FM10K/fm10k) compiled with UIO.
   * `# cd src && make clean && make -j $(nproc) CONFIG_UIO=1 && make install CONFIG_UIO=1`
@@ -11,7 +11,8 @@ Utility that allows dumping the SPI Flash Non-Volatile Memory of the FM10000 fam
   * If this works an UIO device (`/dev/uio0`) will exist. If not, check your bifurcation settings and/or whether the slot supports 16x PCIe 3.0
 
 ## Compilation
-* `make clean && make`
+* `$ make clean && make`
+* You can specify whether to use gcc or clang this way: `$ make CC=gcc` / `$ make CC=clang`
 * An executable named `./fm10k-dump` should now exist.
 
 ## Usage example

fm10k-dump.c

@@ -57,7 +57,7 @@
 #define FM10K_SPI_HEADER_COMMAND_READ_MANUFACTURER_INFORMATION 0x9F
 
 /* Test for GCC >= 4.4.0, see https://gcc.gnu.org/gcc-4.4/changes.html : Packed bit-fields of type char were not properly bit-packed on many targets prior to GCC 4.4 */
-#if __GNUC__ > 4 || (__GNUC__ == 4 && (__GNUC_MINOR__ >= 4))
+#if __GNUC__ > 4 || (__GNUC__ == 4 && (__GNUC_MINOR__ >= 4)) || __clang__
 
 typedef union {
     struct {