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#!/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)
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