commit e46be0f61a89952d9cd984722583bf2101c82318
parent 5a4934636d9eeaada63271c7f58bcdae55ecad60
Author: Robert Russell <robert@rr3.xyz>
Date: Sat, 1 Feb 2025 17:05:10 -0800
Remove bit zips
On second thought, these are too specific for RCX. I moved them to
VCE (the project I originally added them for).
Diffstat:
| M | inc/bits.h | | | 68 | +++++++++----------------------------------------------------------- |
1 file changed, 9 insertions(+), 59 deletions(-)
diff --git a/inc/bits.h b/inc/bits.h
@@ -8,65 +8,15 @@
/* ----- Bit rotates ----- */
-static inline u8 r_rotl8 (u8 n, uint c) { return (n << (c& 7u)) | (n >> (-c& 7u)); }
-static inline u16 r_rotl16(u16 n, uint c) { return (n << (c&15u)) | (n >> (-c&15u)); }
-static inline u32 r_rotl32(u32 n, uint c) { return (n << (c&31u)) | (n >> (-c&31u)); }
-static inline u64 r_rotl64(u64 n, uint c) { return (n << (c&63u)) | (n >> (-c&63u)); }
-
-static inline u8 r_rotr8 (u8 n, uint c) { return (n >> (c& 7u)) | (n << (-c& 7u)); }
-static inline u16 r_rotr16(u16 n, uint c) { return (n >> (c&15u)) | (n << (-c&15u)); }
-static inline u32 r_rotr32(u32 n, uint c) { return (n >> (c&31u)) | (n << (-c&31u)); }
-static inline u64 r_rotr64(u64 n, uint c) { return (n >> (c&63u)) | (n << (-c&63u)); }
-
-
-/* ----- Bit zips ----- */
-
-/* To perform a bit zip with n inputs, we evaluate, over the integers mod 2
- * (where XOR is addition and AND is multiplication), a recursively-structured
- * polynomial with n variables, 2^n terms, and coefficients f0,f1,...,f(2^n-1),
- * the bits of the zipping function f. The pattern is illustrated below for the
- * first few values of n. In principle, we do this independently for each of
- * the 64 n-tuples of input bits, but C's bit-wise operators let us do all 64
- * evaluations in parallel. */
-
-/* TODO: Provide 8, 16, and 32 bit as well? The naming gets awkward, and then
- * there would be 16 functions! */
-
-/* This is the constant polynomial f0. We use a two's complement trick to
- * broadcast f0 to an entire u64. */
-static inline u64
-r_bz0(u64 f) {
- return !(f & 1u) - 1u;
-}
-
-/* f0 ^
- * f1 & u */
-static inline u64
-r_bz1(u64 f, u64 u) {
- return r_bz0(f) ^ (r_bz0(f >> 1) & u);
-}
-
-/* f0 ^
- * f1 & u ^
- * f2 & v ^
- * f3 & u & v */
-static inline u64
-r_bz2(u64 f, u64 u, u64 v) {
- return r_bz1(f, u) ^ (r_bz1(f >> 2, u) & v);
-}
-
-/* f0 ^
- * f1 & u ^
- * f2 & v ^
- * f3 & u & v ^
- * f4 & w ^
- * f5 & u & w ^
- * f6 & v & w ^
- * f7 & u & v & w */
-static inline u64
-r_bz3(u64 f, u64 u, u64 v, u64 w) {
- return r_bz2(f, u, v) ^ (r_bz2(f >> 4, u, v) & w);
-}
+static inline u8 r_rotl8 (u8 n, uint c) { return (n << (c & 7u)) | (n >> (-c & 7u)); }
+static inline u16 r_rotl16(u16 n, uint c) { return (n << (c & 15u)) | (n >> (-c & 15u)); }
+static inline u32 r_rotl32(u32 n, uint c) { return (n << (c & 31u)) | (n >> (-c & 31u)); }
+static inline u64 r_rotl64(u64 n, uint c) { return (n << (c & 63u)) | (n >> (-c & 63u)); }
+
+static inline u8 r_rotr8 (u8 n, uint c) { return (n >> (c & 7u)) | (n << (-c & 7u)); }
+static inline u16 r_rotr16(u16 n, uint c) { return (n >> (c & 15u)) | (n << (-c & 15u)); }
+static inline u32 r_rotr32(u32 n, uint c) { return (n >> (c & 31u)) | (n << (-c & 31u)); }
+static inline u64 r_rotr64(u64 n, uint c) { return (n >> (c & 63u)) | (n << (-c & 63u)); }
/* ----- Population count ----- */
