| #!/usr/bin/env python |
| # This Source Code Form is subject to the terms of the Mozilla Public |
| # License, v. 2.0. If a copy of the MPL was not distributed with this |
| # file, You can obtain one at http://mozilla.org/MPL/2.0/. |
| """Generate tables of immediately-encodable VFP doubles. |
| |
| DOES NOT get automatically run during the build process. If you need to |
| modify this file (which is unlikely), you must re-run this script: |
| |
| python gen-double-encode-table.py > $(topsrcdir)/path/to/DoubleEntryTable.tbl |
| """ |
| |
| import operator |
| |
| def rep(bit, count): |
| return reduce(operator.ior, [bit << c for c in range(count)]) |
| |
| def encodeDouble(value): |
| """Generate an ARM ARM 'VFP modified immediate constant' with format: |
| aBbbbbbb bbcdefgh 000... |
| |
| We will return the top 32 bits of the double; the rest are 0.""" |
| assert (0 <= value) and (value <= 255) |
| a = value >> 7 |
| b = (value >> 6) & 1 |
| B = int(b == 0) |
| cdefgh = value & 0x3f |
| return (a << 31) | (B << 30) | (rep(b, 8) << 22) | cdefgh << 16 |
| |
| print '/* THIS FILE IS AUTOMATICALLY GENERATED BY gen-double-encode-table.py. */' |
| for i in range(256): |
| print ' { 0x%08x, { %d, %d, 0 } },' % (encodeDouble(i), i & 0xf, i >> 4) |
