1 files changed, 35 insertions, 0 deletions
diff --git a/js/src/jit/arm/gen-double-encoder-table.py b/js/src/jit/arm/gen-double-encoder-table.py
new file mode 100644
index 0000000000..fd622da82e
--- /dev/null
+++ b/js/src/jit/arm/gen-double-encoder-table.py
@@ -0,0 +1,35 @@
+#!/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))