eval: add general support for "integer functions" and add ilog2*()

Add general support in the function parser for "integer functions"
(actually implemented as special unary operators, then wrapped in
macros) and implement a family of integer logarithms.  The only
difference is the behavior on a non-power-of-two argument:

	ilog2[e]	-- throw an error
	ilog2w		-- throw a warning
	ilog2f		-- round down to power of 2
	ilog2c		-- round up to power of 2

This is useful for back-converting from masks to bit values.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/tokens.dat b/tokens.dat
index bb5fccb..c2df469 100644
--- a/tokens.dat
+++ b/tokens.dat
@@ -97,6 +97,12 @@ __utf32__
 __utf32le__
 __utf32be__
 
+% TOKEN_IFUNC, 0, IFUNC_{__*__}
+__ilog2e__
+__ilog2w__
+__ilog2f__
+__ilog2c__
+
 % TOKEN_*, 0, 0
 seg
 wrt