util/bitset: fix bitset range mask calculations.

The MASK macro is used in the RANGE macro, and it should
return the pre-bitset word mask for the (b) value.

i.e.
BITSET_MASK(0) should be undefined since it's meaningless.
BITSET_MASK(31) should give 0x7fffffff
BITSET_MASK(32) should give 0xffffffff
BITSET_MASK(33) should give 0x00000001
BITSET_MASK(64) should give 0xffffffff

However then BITSET_RANGE ends up broken for cases where
it's (b) value is the 0,32,64 value as in that case the lower
mask would be 0 not 0xffffffff.

This fixes the unit tests that I've added, and my code that
uses bitsets.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Fixes: bb38cadb1c5f2 "More GLSL code"
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>

diff --git a/src/util/bitset.h b/src/util/bitset.h
index e610d5f897ec0137e58a87940565b93fc04c8ea9..7f116214b920c0b8431e76f8093d8829428dc80c 100644 (file)
--- a/src/util/bitset.h
+++ b/src/util/bitset.h
@@ -62,8 +62,8 @@
 #define BITSET_SET(x, b) ((x)[BITSET_BITWORD(b)] |= BITSET_BIT(b))
 #define BITSET_CLEAR(x, b) ((x)[BITSET_BITWORD(b)] &= ~BITSET_BIT(b))
 
-#define BITSET_MASK(b) ((b) == BITSET_WORDBITS ? ~0 : BITSET_BIT(b) - 1)
-#define BITSET_RANGE(b, e) (BITSET_MASK((e) + 1) & ~BITSET_MASK(b))
+#define BITSET_MASK(b) (((b) % BITSET_WORDBITS == 0) ? ~0 : BITSET_BIT(b) - 1)
+#define BITSET_RANGE(b, e) ((BITSET_MASK((e) + 1)) & ~(BITSET_BIT(b) - 1))
 
 /* bit range operations
  */