AVR Bazel build rules

This directory contains some special Bazel build rules to produce joint x86 and AVR build targets. This allows defining a single target definition per BUILD file to produce libraries for both targets, to avoid having to double-declare them.

An AVR library can be defined in the same way a C++ library is defined:

avr_library(
  name = "my_library",
  hdrs = ["my_lib.h"],
  srcs = ["my_lib.cpp"],
  deps = [":my_other_library"],
)

This produces a traditional x86 cc_library target called my_library, and an AVR target called my_library_avr. An AVR-only library can be produced with avr_pure_library:

avr_pure_library(
  name = "my_pure_library",
  hdrs = ["my_pure_lib.h"],
  srcs = ["my_pure_lib.cpp"],
  deps = [":my_other_library"],
)

This will only produce an AVR target called my_pure_library_avr. See the full list of rules below for more rules and info.

Using these rules

To use these rules, add the following to your WORKSPACE file:

load(
  "@bazel_tools//tools/build_defs/repo:git.bzl",
  "git_repository",
)

git_repository(
  name = "avr-bazel",
  branch = "master",
  remote = "https://github.com/taylorconor/avr-bazel",
)

# initialise the avr-basel rules.
load(
  "@avr-bazel//:avr.bzl",
  "avr_tools_repository",
)
avr_tools_repository()

List of rules

avr.bzl contains a number of rule definitions to work with AVR libraries and binaries:

• avr_library: similar to cc_library, produces a regular cc_library target along with an AVR target, with name original_target_name*_avr*.
• avr_pure_library: similar to avr_library except does not produce a cc_library target.
• avr_binary: similar to cc_binary, produces an AVR binary file.
• avr_hex: produces a hex file to be used for flashing AVR microcontrollers.

Any cc_library or cc_test targeting non-AVR targets can depend on avr_library targets and will automatically depend on the non-AVR version of that target. This is because avr_library is a rule that produces two targets. One regular cc_library target, and one avr_pure_library target, with a name ending in _avr.

Please note that this is not a complete toolchain, but rather a rule that generates other rules. This has a number of limitations, including being less portable than a complete toolchain, and producing hidden target names (ending in _avr).