Build a CPP file with ICU data for WASM.
Emscripten does not work with assembly files, and we cannot
load a file at runtime. So, to get the ICU data into a WASM
build, we generate a CPP file with the data and compile that.
Bug: 1300013
Change-Id: I191069713500e8346cefe7d50a23f1f753d247be
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/deps/icu/+/3482537
Reviewed-by: Frank Tang <ftang@chromium.org>
diff --git a/scripts/make_data_cpp.py b/scripts/make_data_cpp.py
new file mode 100644
index 0000000..d9f862f
--- /dev/null
+++ b/scripts/make_data_cpp.py
@@ -0,0 +1,66 @@
+#!/usr/bin/env python
+
+# Copyright 2022 Google LLC.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+'''
+Generate a source file containing the given binary data.
+
+Output type is C++.
+
+This is required for a WASM build because the Emscripten toolchain cannot
+load data files using file I/O, nor can it consume assembly files.
+
+This is in use by the Flutter web engine and Skia CanvasKit. See
+[this](https://github.com/google/skia/blob/main/modules/canvaskit/README.md)
+for an example of a build using this.
+'''
+
+from __future__ import print_function
+
+import os
+import struct
+import sys
+import mmap
+
+def get_version_number(path):
+ input_data = open(path, 'rb').read()
+ n = input_data.find(b'icudt')
+ if n == -1:
+ exit("Cannot find a version number in %s." % path)
+
+ return input_data[n + 5:n + 7].decode("ascii")
+
+def iterate_as_uint32(path):
+ with open(path, 'rb') as f:
+ s = struct.Struct('@I')
+ assert s.size == 4
+ mm = mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ)
+ assert (len(mm) % s.size) == 0
+ for offset in range(0, len(mm), s.size):
+ yield s.unpack_from(mm, offset)[0]
+ mm.close()
+
+
+def convert(fmt, src_path, dst_path):
+ header, line_begin, line_end, footer = fmt
+ assert os.path.exists(src_path)
+ version_number = get_version_number(src_path)
+ name = 'icudt%s_dat' % version_number
+ src = iterate_as_uint32(src_path)
+ with open(dst_path, 'w') as o:
+ o.write(header.format(name))
+ while True:
+ line = ','.join('%d' % v for _, v in zip(range(8), src))
+ if not line:
+ break
+ o.write('%s%s%s\n' % (line_begin, line, line_end))
+ o.write(footer.format(name))
+
+
+cpp = ('#include <cstdint>\nextern "C" uint32_t {0}[] __attribute__((aligned(16))) = {{\n',
+ '', ',', '}};\n')
+
+if __name__ == '__main__':
+ convert(cpp, sys.argv[1], sys.argv[2])