crypto: sha256_generic - Use 64-bit counter like sha1

This patch replaces the two 32-bit counter code in sha256_generic
with the simpler 64-bit counter code from sha1.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 30 insertions, 35 deletions

diff --git a/crypto/sha256_generic.c b/crypto/sha256_generic.c
index 6349d8339d3..e58c71bdf33 100644
--- a/crypto/sha256_generic.c
+++ b/crypto/sha256_generic.c
@@ -26,7 +26,7 @@
 #include <asm/byteorder.h>
 
 struct sha256_ctx {
-        u32 count[2];
+        u64 count;
         u32 state[8];
         u8 buf[128];
 };
@@ -231,8 +231,7 @@ static int sha224_init(struct shash_desc *desc)
         sctx->state[5] = SHA224_H5;
         sctx->state[6] = SHA224_H6;
         sctx->state[7] = SHA224_H7;
-        sctx->count[0] = 0;
-        sctx->count[1] = 0;
+        sctx->count = 0;
 
         return 0;
 }
@@ -248,7 +247,7 @@ static int sha256_init(struct shash_desc *desc)
         sctx->state[5] = SHA256_H5;
         sctx->state[6] = SHA256_H6;
         sctx->state[7] = SHA256_H7;
-        sctx->count[0] = sctx->count[1] = 0;
+        sctx->count = 0;
 
         return 0;
 }
@@ -257,33 +256,30 @@ static int sha256_update(struct shash_desc *desc, const u8 *data,
                           unsigned int len)
 {
         struct sha256_ctx *sctx = shash_desc_ctx(desc);
-        unsigned int i, index, part_len;
-
-        /* Compute number of bytes mod 128 */
-        index = (unsigned int)((sctx->count[0] >> 3) & 0x3f);
-
-        /* Update number of bits */
-        if ((sctx->count[0] += (len << 3)) < (len << 3)) {
-                sctx->count[1]++;
-                sctx->count[1] += (len >> 29);
+        unsigned int partial, done;
+        const u8 *src;
+
+        partial = sctx->count & 0x3f;
+        sctx->count += len;
+        done = 0;
+        src = data;
+
+        if ((partial + len) > 63) {
+                if (partial) {
+                        done = -partial;
+                        memcpy(sctx->buf + partial, data, done + 64);
+                        src = sctx->buf;
+                }
+
+                do {
+                        sha256_transform(sctx->state, src);
+                        done += 64;
+                        src = data + done;
+                } while (done + 63 < len);
+
+                partial = 0;
         }
-
-        part_len = 64 - index;
-
-        /* Transform as many times as possible. */
-        if (len >= part_len) {
-                memcpy(&sctx->buf[index], data, part_len);
-                sha256_transform(sctx->state, sctx->buf);
-
-                for (i = part_len; i + 63 < len; i += 64)
-                        sha256_transform(sctx->state, &data[i]);
-                index = 0;
-        } else {
-                i = 0;
-        }
-
-        /* Buffer remaining input */
-        memcpy(&sctx->buf[index], &data[i], len-i);
+        memcpy(sctx->buf + partial, src, len - done);
 
         return 0;
 }
@@ -292,22 +288,21 @@ static int sha256_final(struct shash_desc *desc, u8 *out)
 {
         struct sha256_ctx *sctx = shash_desc_ctx(desc);
         __be32 *dst = (__be32 *)out;
-        __be32 bits[2];
+        __be64 bits;
         unsigned int index, pad_len;
         int i;
         static const u8 padding[64] = { 0x80, };
 
         /* Save number of bits */
-        bits[1] = cpu_to_be32(sctx->count[0]);
-        bits[0] = cpu_to_be32(sctx->count[1]);
+        bits = cpu_to_be64(sctx->count << 3);
 
         /* Pad out to 56 mod 64. */
-        index = (sctx->count[0] >> 3) & 0x3f;
+        index = sctx->count & 0x3f;
         pad_len = (index < 56) ? (56 - index) : ((64+56) - index);
         sha256_update(desc, padding, pad_len);
 
         /* Append length (before padding) */
-        sha256_update(desc, (const u8 *)bits, sizeof(bits));
+        sha256_update(desc, (const u8 *)&bits, sizeof(bits));
 
         /* Store state in digest */
         for (i = 0; i < 8; i++)