From 1655e4a0e23a8c51d8200b1506be891e1512c6dd Mon Sep 17 00:00:00 2001
From: Mark Wooding <mdw@distorted.org.uk>
Date: Wed, 31 Oct 2018 12:03:16 +0000
Subject: [PATCH] symm/blkc.h: Add macros for binary-field shifts.

---
 symm/blkc.h | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)

diff --git a/symm/blkc.h b/symm/blkc.h
index 52179dfb..bbba7631 100644
--- a/symm/blkc.h
+++ b/symm/blkc.h
@@ -299,6 +299,94 @@
   BLKC_GLUE(BLKC_SKEL_, n)						\
     (PRE, BLKC_W(w); const BLKC_WX(wx);, op, BLKC_XMOVE_GUTS)
 
+/*----- Binary field arithmetic -------------------------------------------*/
+
+#define BLKC_POLY_IRRED64  0x001b
+#define BLKC_POLY_IRRED96  0x0641
+#define BLKC_POLY_IRRED128 0x0087
+#define BLKC_POLY_IRRED192 0x0087
+#define BLKC_POLY_IRRED256 0x0425
+
+#define BLKC_POLY_PRIM64   0x001b
+#define BLKC_POLY_PRIM96   0x0641
+#define BLKC_POLY_PRIM128  0x0087
+#define BLKC_POLY_PRIM192  0x8821
+#define BLKC_POLY_PRIM256  0x0425
+
+#define BLKC_POLY(PRE, f) BLKC_GLUE(BLKC_POLY_##f, BLKC_BITS(PRE))
+
+#define BLKC_BLSHIFT(PRE, f, z, x)					\
+  BLKC_GLUE(BLKC_BLSHIFT_X_, BLKC_ENDIAN(PRE))				\
+    (PRE, f, z, x)
+#define BLKC_LLSHIFT(PRE, f, z, x)					\
+  BLKC_GLUE(BLKC_LLSHIFT_X_, BLKC_ENDIAN(PRE))				\
+    (PRE, f, z, x)
+#define BLKC_LSHIFT(PRE, f, z, x)					\
+  BLKC_GLUE(BLKC_LSHIFT_X_, BLKC_ENDIAN(PRE))				\
+    (PRE, BLKC_ID, f, z, x)
+
+#define BLKC_BRSHIFT(PRE, f, z, x)					\
+  BLKC_GLUE(BLKC_BRSHIFT_X_, BLKC_ENDIAN(PRE))				\
+    (PRE, f, z, x)
+#define BLKC_LRSHIFT(PRE, f, z, x)					\
+  BLKC_GLUE(BLKC_LRSHIFT_X_, BLKC_ENDIAN(PRE))				\
+    (PRE, f, z, x)
+#define BLKC_RSHIFT(PRE, f, z, x)					\
+  BLKC_GLUE(BLKC_RSHIFT_X_, BLKC_ENDIAN(PRE))				\
+    (PRE, BLKC_ID, f, z, x)
+
+#define BLKC_BLSHIFT_X_B(PRE, f, z, x) BLKC_LSHIFT_X_B(PRE, BLKC_ID, f, z, x)
+#define BLKC_LLSHIFT_X_B(PRE, f, z, x) BLKC_LSHIFT_X_L(PRE, ENDSWAP32, f, z, x)
+#define BLKC_BLSHIFT_X_L(PRE, f, z, x) BLKC_LSHIFT_X_B(PRE, ENDSWAP32, f, z, x)
+#define BLKC_LLSHIFT_X_L(PRE, f, z, x) BLKC_LSHIFT_X_L(PRE, BLKC_ID, f, z, x)
+
+#define BLKC_BRSHIFT_X_B(PRE, f, z, x) BLKC_RSHIFT_X_B(PRE, BLKC_ID, f, z, x)
+#define BLKC_LRSHIFT_X_B(PRE, f, z, x) BLKC_RSHIFT_X_L(PRE, ENDSWAP32, f, z, x)
+#define BLKC_BRSHIFT_X_L(PRE, f, z, x) BLKC_RSHIFT_X_B(PRE, ENDSWAP32, f, z, x)
+#define BLKC_LRSHIFT_X_L(PRE, f, z, x) BLKC_RSHIFT_X_L(PRE, BLKC_ID, f, z, x)
+
+#define BLKC_LSHIFT_X_B(PRE, op, f, z, x) do {				\
+  uint32 *_z = (z); const uint32 *_x = (x);				\
+  uint32 _t = op(_x[0]), _m = -(uint32)((_t >> 31)&1u),			\
+    _c = BLKC_POLY(PRE, f)&_m;						\
+  unsigned _i;								\
+									\
+  for (_i = PRE##_BLKSZ/4; _i-- > 0; )					\
+    { _t = op(_x[_i]); _z[_i] = op((_t << 1) ^ _c); _c = (_t >> 31)&1u; } \
+} while (0)
+
+#define BLKC_RSHIFT_X_B(PRE, op, f, z, x) do {				\
+  uint32 *_z = (z); const uint32 *_x = (x);				\
+  uint32 _t, _t0 = op(_x[PRE##_BLKSZ/4 - 1]), _m = -(uint32)(_t0&1u),	\
+    _c = 0x80000000&_m;							\
+  unsigned _i;								\
+									\
+  for (_i = 0; _i < PRE##_BLKSZ/4 - 1; _i++)				\
+    { _t = op(_x[_i]); _z[_i] = op((_t >> 1) ^ _c); _c = (_t&1u) << 31; } \
+  _t0 ^= BLKC_POLY(PRE, f)&_m; _z[PRE##_BLKSZ/4 - 1] = op((_t0 >> 1) ^ _c); \
+} while (0)
+
+#define BLKC_LSHIFT_X_L(PRE, op, f, z, x) do {				\
+  uint32 *_z = (z); const uint32 *_x = (x);				\
+  uint32 _t = op(_x[PRE##_BLKSZ/4 - 1]), _m = -(uint32)((_t >> 31)&1u),	\
+    _c = BLKC_POLY(PRE, f)&_m;						\
+  unsigned _i;								\
+									\
+  for (_i = 0; _i < PRE##_BLKSZ/4; _i++)				\
+    { _t = op(_x[_i]); _z[_i] = op((_t << 1) ^ _c); _c = (_t >> 31)&1u; } \
+} while (0)
+
+#define BLKC_RSHIFT_X_L(PRE, op, f, z, x) do {				\
+  uint32 *_z = (z); const uint32 *_x = (x);				\
+  uint32 _t, _t0 = op(_x[0]), _m = -(uint32)(_t0&1u),			\
+    _c = 0x80000000&_m;							\
+  unsigned _i;								\
+									\
+  for (_i = PRE##_BLKSZ/4 - 1; _i-- > 1; )				\
+    { _t = op(_x[_i]); _z[_i] = op((_t >> 1) ^ _c); _c = (_t&1u) << 31; } \
+  _t0 ^= BLKC_POLY(PRE, f)&_m; _z[0] = op((_t0 >> 1) ^ _c);		\
+} while (0)
+
 /*----- Test rig for block ciphers ----------------------------------------*/
 
 /* --- @BLKC_TEST@ --- *
-- 
2.11.0