1 files changed, 65 insertions, 0 deletions
diff --git a/riscv/insns/vaeskf1_vi.h b/riscv/insns/vaeskf1_vi.h
new file mode 100644
index 0000000..28d03d0
--- /dev/null
+++ b/riscv/insns/vaeskf1_vi.h
@@ -0,0 +1,65 @@
+// vaeskf1.vi vd, vs2, rnd
+
+#include "zvk_ext_macros.h"
+#include "zvkned_ext_macros.h"
+
+require_vaeskf_vi_constraints;
+
+// There is one round constant for each round number
+// between 1 and 10. We index using 'round# -1'.
+static constexpr uint8_t kRoundConstants[10] = {
+  0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
+};
+
+// For AES128, AES192, or AES256, keys (and state) are handled as
+// 128b/16B values.
+//
+// The Zvkned spec calls for handling the vector as made of EGU32x4
+// element groups (i.e., 4 uint32_t), and FIPS-197 AES specification
+// describes the key expansion in terms of manipulations of 32 bit
+// words, so using the EGU32x4 is natural.
+//
+VI_ZVK_VD_VS2_ZIMM5_EGU32x4_NOVM_LOOP(
+  {},
+  // The following statements will be executed before the first execution
+  // of the loop, and only if the loop is going to be entered.
+  // We cannot use a block ( { ... } ) since we want the 'round' variable
+  // declared and defined here  here to be visible in the loop block.
+  // Only consider the bottom 4 bits of the immediate.
+  const reg_t zimm4 = zimm5 & 0xF;
+  // Normalize the round value to be in [2, 14] by toggling bit 3
+  // if outside the range (i.e., +8 or -8).
+  const reg_t round = ((1 <= zimm4) && (zimm4 <= 10)) ? zimm4 : (zimm4 ^ 0x8);
+  const uint32_t rcon = kRoundConstants[round - 1];,
+  // Per Element Group body.
+  {
+    // vaeskf1_vi produces key[i+1] in vd, it receives key[i] in vs2,
+    // i.e., 4x32b values (4 words).
+    //
+    // The logic is fairly similar between vaeskf1/vaeskf2, with the following
+    // differences:
+    // - in AES-128 (vaeskf1), we get both the 'temp' word and
+    //   the "previous words" w0..w3 from key[i]/vs2.
+    // - in AES-256 (vaeskf2), we get 'temp' from key[i]/vs2, and
+    //   the "previous words" w0..w3 from key[i-1]/vd.
+
+    // 'temp' is extracted from the last (most significant) word of key[i].
+    uint32_t temp = vs2[3];
+    temp = (temp >> 8) | (temp << 24);  // Rotate right by 8
+    temp = (((uint32_t)AES_ENC_SBOX[(temp >> 24) & 0xFF] << 24) |
+            ((uint32_t)AES_ENC_SBOX[(temp >> 16) & 0xFF] << 16) |
+            ((uint32_t)AES_ENC_SBOX[(temp >>  8) & 0xFF] <<  8) |
+            ((uint32_t)AES_ENC_SBOX[(temp >>  0) & 0xFF] <<  0));
+    temp = temp ^ rcon;
+
+    // "old" words are the w[i-Nk] of FIPS-197. They are extracted
+    // from vs2, which contains key[i] in AES-128 where Nk=4.
+    const uint32_t w0 = vs2[0] ^ temp;
+    const uint32_t w1 = vs2[1] ^ w0;
+    const uint32_t w2 = vs2[2] ^ w1;
+    const uint32_t w3 = vs2[3] ^ w2;
+
+    // Overwrite vd with k[i+1] from the new words.
+    SET_EGU32x4_LE(vd, w0, w1, w2, w3);
+  }
+);