added script to generate .cargo/config from toolchain environment 💪

.gitignore

@@ -74,3 +74,6 @@ modules.order
 Module.symvers
 Mkfile.old
 dkms.conf
+
+#.cargo config dir
+.cargo

README.md

@@ -23,24 +23,24 @@ In order to build `libremarkable` and the examples (`spy.so` and `demo`), you'll
 
 You can then set up your Rust toolchain for cross compilation with: `rustup target add armv7-unknown-linux-gnueabihf`.
 
-Once that's done, you should add the following to `.cargo/config` (replace `<path-to-installed-oecore-toochain>` with the directory you installed the Remarkable toolchain to):
+In order for rust to leverage the toolchain a `.cargo/config` file is required. This file can be generated using the `gen_cargo_config.py`. First the toolchain environment must be
+sourced. It location is can be found within the toolchain installation directory. The correct path is also referenced in the toolchain [wiki](https://remarkablewiki.com/devel/toolchain).
+After the environment is loaded the script will read the environment variables to generate the correct `.cargo/config` file for your toolchain.
+
+The resulting config file will look something like this:
 ```
 [target.armv7-unknown-linux-gnueabihf]
-linker = "<path-to-the-installed-oecore-toolchain>/sysroots/x86_64-oesdk-linux/usr/bin/arm-oe-linux-gnueabi/arm-oe-linux-gnueabi-gcc"
+linker = "<toolchain_install_path>/sysroots/x86_64-codexsdk-linux/usr/bin/arm-remarkable-linux-gnueabi/arm-remarkable-linux-gnueabi-gcc"
 rustflags = [
   "-C", "link-arg=-march=armv7-a",
   "-C", "link-arg=-marm",
   "-C", "link-arg=-mfpu=neon",
   "-C", "link-arg=-mfloat-abi=hard",
   "-C", "link-arg=-mcpu=cortex-a9",
-  "-C", "link-arg=--sysroot=<path-to-the-installed-oecore-toolchain>/sysroots/cortexa9hf-neon-oe-linux-gnueabi",
+  "-C", "link-arg=--sysroot=<toolchain_install_path>/sysroots/cortexa7hf-neon-remarkable-linux-gnueabi",
 ]
 ```
 
-(`<path-to-the-installed-oecore-toolchain` will likely be `/usr/local/oecore-x86_64/`, if you did the default install on Linux.)
-
-If you have further questions, feel free to ask in Issues.
-
 You can also add this snippet to the above file in order to default to cross-compiling for this project:
 
 ```

gen_cargo_config.py

@@ -0,0 +1,47 @@
+#!/usr/bin/env python3
+
+import os
+import re
+
+cargo_config = """
+[target.armv7-unknown-linux-gnueabihf]
+linker = "{gcc_path}"
+rustflags = [
+  "-C", "link-arg=-march=armv7-a",
+  "-C", "link-arg=-marm",
+  "-C", "link-arg={fpu}",
+  "-C", "link-arg={float_s}",
+  "-C", "link-arg={cpu}",
+  "-C", "link-arg=--sysroot={sysroot}",
+]\n"""
+
+def main():
+    #get sysroot from environment
+    sysroot = os.environ["SDKTARGETSYSROOT"]
+    #get comiler name from environment
+    cc_full = os.environ["CC"]
+    cc = cc_full.split(" ")[0]
+    #strip -gcc from compiler to build regex string for parsing PATH
+    cc_path = cc[0:-4]
+    re_parse_path = ":[^:]*{cc}:".format(cc=cc_path)
+    extract_compiler_path = re.compile(re_parse_path)
+    toolchain_compiler_path = extract_compiler_path.search(os.environ["PATH"]).group(0)[1:-1]
+    #get other arguments from compiler definition
+    re_fpu = re.compile("(-mfpu=[^ ]*)")
+    re_float = re.compile("(-mfloat-abi=[^ ]*)")
+    re_cpu = re.compile("(-mcpu=[^ ]*)")
+    fpu_arg = re_fpu.search(cc_full).group(0)
+    float_arg = re_float.search(cc_full).group(0)
+    cpu_arg = re_cpu.search(cc_full).group(0)
+    #join path to get full compiler path
+    cc = os.path.join(toolchain_compiler_path, cc)
+
+    #create .cargo dir if not exsits
+    if not os.path.isdir(".cargo"):
+        os.mkdir(".cargo")
+    with open(".cargo/config","w") as f:
+        f.write(cargo_config.format(gcc_path=cc, sysroot=sysroot, fpu=fpu_arg, float_s=float_arg, cpu=cpu_arg))
+    print("Toolchain config written to \".cargo/config\" ✅")
+
+if __name__ == "__main__":
+    main()