# Copyright 2014 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

# This provides the yasm_assemble() template which uses YASM to assemble
# assembly files.
#
# Files to be assembled with YASM should have an extension of .asm.
#
# Parameters
#
#   yasm_flags (optional)
#       [list of strings] Pass additional flags into YASM. These are appended
#       to the command line. Note that the target machine type and system is
#       already set up based on the current toolchain so you don't need to
#       specify these things (see below).
#
#       Example: yasm_flags = [ "--force-strict" ]
#
#   include_dirs (optional)
#       [list of dir names] List of additional include dirs. Note that the
#       source root and the root generated file dir is always added, just like
#       our C++ build sets up.
#
#       Example: include_dirs = [ "//some/other/path", target_gen_dir ]
#
#   defines (optional)
#       [list of strings] List of defines, as with the native code defines.
#
#       Example: defines = [ "FOO", "BAR=1" ]
#
#   source_prereqs, deps, visibility  (optional)
#       These have the same meaning as in an action.
#
# Example
#
#   yasm_assemble("my_yasm_target") {
#     sources = [
#       "ultra_optimized_awesome.asm",
#     ]
#     include_dirs = [ "assembly_include" ]
#   }

if (is_mac || is_ios) {
  if (cpu_arch == "x86") {
    _yasm_flags = [
      "-fmacho32",
      "-m", "x86",
    ]
  } else if (cpu_arch == "x64") {
    _yasm_flags = [
      "-fmacho64",
      "-m", "amd64",
    ]
  }
} else if (is_posix) {
  if (cpu_arch == "x86") {
    _yasm_flags = [
      "-felf32",
      "-m", "x86",
    ]
  } else if (cpu_arch == "x64") {
    _yasm_flags = [
      "-DPIC",
      "-felf64",
      "-m", "amd64",
    ]
  }
} else if (is_win) {
  if (cpu_arch == "x86") {
    _yasm_flags = [
      "-DPREFIX",
      "-fwin32",
      "-m", "x86",
    ]
  } else if (cpu_arch == "x64") {
    _yasm_flags = [
      "-fwin64",
      "-m", "amd64",
    ]
  }
}

# Default yasm include dirs. Make it match the native build (source root and
# root generated code directory).
_yasm_flags += [
  # Using "//." will produce a relative path "../.." which looks better than
  # "../../" which will result from using "//" as the base (although both
  # work). This is because rebase_path will terminate the result in a slash if
  # the input ends in a slash.
  "-I" + rebase_path("//.", root_build_dir),
  "-I" + rebase_path(root_gen_dir, root_build_dir),
]

if (is_win) {
  asm_obj_extension = "obj"
} else {
  asm_obj_extension = "o"
}

template("yasm_assemble") {
  # TODO(ajwong): Support use_system_yasm.
  assert(defined(invoker.sources), "Need sources defined for $target_name")

  # Only depend on YASM on x86 systems. Force compilation of .asm files for
  # ARM to fail.
  assert(cpu_arch == "x86" || cpu_arch == "x64")

  action_name = "${target_name}_action"
  source_set_name = target_name

  action_foreach(action_name) {
    visibility = ":$source_set_name"  # Only the source set can depend on this.

    script = "//third_party/yasm/run_yasm.py"
    sources = invoker.sources

    if (defined(invoker.source_prereqs)) {
      source_prereqs = invoker.source_prereqs
    }

    # Executable (first in the args). The binary might be in the root build dir
    # (no cross-compiling) or in a toolchain-specific subdirectory of that
    # (when cross-compiling).
    yasm_label = "//third_party/yasm($host_toolchain)"
    args = [ "./" +  # Force current dir.
      rebase_path(get_label_info(yasm_label, "root_out_dir") + "/yasm",
                  root_build_dir)
    ]

    # Deps.
    deps = [ yasm_label ]
    if (defined(invoker.deps)) {
      deps += invoker.deps
    }

    # Flags.
    args += _yasm_flags
    if (defined(invoker.yasm_flags)) {
      args += invoker.yasm_flags
    }

    # Extra include directories.
    if (defined(invoker.include_dirs)) {
      foreach(include, invoker.include_dirs) {
        args += [ "-I" + rebase_path(include, root_build_dir) ]
      }
    }

    # Extra defines.
    if (defined(invoker.defines)) {
      foreach(def, invoker.defines) {
        args += [ "-D$def" ]
      }
    }

    # Output file.
    #
    # TODO(brettw) it might be nice if there was a source expansion for the
    # path of the source file relative to the source root. Then we could
    # exactly duplicate the naming and location of object files from the
    # native build, which would be:
    # "$root_out_dir/${target_name}.{{source_dir_part}}.$asm_obj_extension"
    outputs = [ "$target_out_dir/{{source_name_part}}.o" ]
    args += [
      "-o", rebase_path(outputs[0], root_build_dir),
      "{{source}}"
    ]

    # The wrapper script run_yasm will write the depfile to the same name as
    # the output but with .d appended (like gcc will).
    depfile = outputs[0] + ".d"
  }

  # Gather the .o files into a linkable thing. This doesn't actually link
  # anything (a source set just compiles files to link later), but will pass
  # the object files generated by the action up the dependency chain.
  source_set(source_set_name) {
    if (defined(invoker.visibility)) {
      visibility = invoker.visibility
    }

    sources = get_target_outputs(":$action_name")
  }
}