sha3: code shrink

function                                             old     new   delta
sha3_hash                                            155     101     -54

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 59 insertions, 32 deletions

diff --git a/libbb/hash_md5_sha.c b/libbb/hash_md5_sha.c
index d23d4f639..b4d955e5a 100644
--- a/libbb/hash_md5_sha.c
+++ b/libbb/hash_md5_sha.c
@@ -56,7 +56,7 @@ static void FAST_FUNC common64_hash(md5_ctx_t *ctx, const void *buffer, size_t l
                 len -= remaining;
                 buffer = (const char *)buffer + remaining;
                 bufpos += remaining;
-                /* clever way to do "if (bufpos != 64) break; ... ; bufpos = 0;" */
+                /* Clever way to do "if (bufpos != N) break; ... ; bufpos = 0;" */
                 bufpos -= 64;
                 if (bufpos != 0)
                         break;
@@ -839,7 +839,7 @@ void FAST_FUNC sha512_hash(sha512_ctx_t *ctx, const void *buffer, size_t len)
                 len -= remaining;
                 buffer = (const char *)buffer + remaining;
                 bufpos += remaining;
-                /* clever way to do "if (bufpos != 128) break; ... ; bufpos = 0;" */
+                /* Clever way to do "if (bufpos != N) break; ... ; bufpos = 0;" */
                 bufpos -= 128;
                 if (bufpos != 0)
                         break;
@@ -1079,63 +1079,90 @@ void FAST_FUNC sha3_begin(sha3_ctx_t *ctx)
         memset(ctx, 0, sizeof(*ctx));
 }
 
-void FAST_FUNC sha3_hash(sha3_ctx_t *ctx, const void *buf, size_t bytes)
+void FAST_FUNC sha3_hash(sha3_ctx_t *ctx, const void *buffer, size_t len)
 {
-        const uint8_t *data = buf;
-        unsigned bytes_queued = ctx->bytes_queued;
+#if SHA3_SMALL
+        const uint8_t *data = buffer;
+        unsigned bufpos = ctx->bytes_queued;
+
+        while (1) {
+                unsigned remaining = SHA3_IBLK_BYTES - bufpos;
+                if (remaining > len)
+                        remaining = len;
+                len -= remaining;
+                /* XOR data into buffer */
+                while (remaining != 0) {
+                        uint8_t *buf = (uint8_t*)ctx->state;
+                        buf[bufpos] ^= *data++;
+                        bufpos++;
+                        remaining--;
+                }
+                /* Clever way to do "if (bufpos != N) break; ... ; bufpos = 0;" */
+                bufpos -= SHA3_IBLK_BYTES;
+                if (bufpos != 0)
+                        break;
+                /* Buffer is filled up, process it */
+                sha3_process_block72(ctx->state);
+                /*bufpos = 0; - already is */
+        }
+        ctx->bytes_queued = bufpos + SHA3_IBLK_BYTES;
+#else
+        /* +50 bytes code size, but a bit faster because of long-sized XORs */
+        const uint8_t *data = buffer;
+        unsigned bufpos = ctx->bytes_queued;
 
         /* If already data in queue, continue queuing first */
-        while (bytes != 0 && bytes_queued != 0) {
-                uint8_t *buffer = (uint8_t*)ctx->state;
-                buffer[bytes_queued] ^= *data++;
-                bytes--;
-                bytes_queued++;
-                if (bytes_queued == SHA3_IBLK_BYTES) {
-                        sha3_process_block72(ctx->state);
-                        bytes_queued = 0;
+        while (len != 0 && bufpos != 0) {
+                uint8_t *buf = (uint8_t*)ctx->state;
+                buf[bufpos] ^= *data++;
+                len--;
+                bufpos++;
+                if (bufpos == SHA3_IBLK_BYTES) {
+                        bufpos = 0;
+                        goto do_block;
                 }
         }
 
         /* Absorb complete blocks */
-        while (bytes >= SHA3_IBLK_BYTES) {
+        while (len >= SHA3_IBLK_BYTES) {
                 /* XOR data onto beginning of state[].
-                 * We try to be efficient - operate on word at a time, not byte.
-                 * Yet safe wrt unaligned access: can't just use "*(long*)data"...
+                 * We try to be efficient - operate one word at a time, not byte.
+                 * Careful wrt unaligned access: can't just use "*(long*)data"!
                  */
                 unsigned count = SHA3_IBLK_BYTES / sizeof(long);
-                long *buffer = (long*)ctx->state;
+                long *buf = (long*)ctx->state;
                 do {
                         long v;
                         move_from_unaligned_long(v, (long*)data);
-                        *buffer++ ^= v;
+                        *buf++ ^= v;
                         data += sizeof(long);
                 } while (--count);
-
+                len -= SHA3_IBLK_BYTES;
+ do_block:
                 sha3_process_block72(ctx->state);
-
-                bytes -= SHA3_IBLK_BYTES;
         }
 
         /* Queue remaining data bytes */
-        while (bytes != 0) {
-                uint8_t *buffer = (uint8_t*)ctx->state;
-                buffer[bytes_queued] ^= *data++;
-                bytes_queued++;
-                bytes--;
+        while (len != 0) {
+                uint8_t *buf = (uint8_t*)ctx->state;
+                buf[bufpos] ^= *data++;
+                bufpos++;
+                len--;
         }
 
-        ctx->bytes_queued = bytes_queued;
+        ctx->bytes_queued = bufpos;
+#endif
 }
 
-void FAST_FUNC sha3_end(sha3_ctx_t *ctx, uint8_t *hashval)
+void FAST_FUNC sha3_end(sha3_ctx_t *ctx, void *resbuf)
 {
         /* Padding */
-        uint8_t *buffer = (uint8_t*)ctx->state;
-        buffer[ctx->bytes_queued]   ^= 1;
-        buffer[SHA3_IBLK_BYTES - 1] ^= 0x80;
+        uint8_t *buf = (uint8_t*)ctx->state;
+        buf[ctx->bytes_queued]   ^= 1;
+        buf[SHA3_IBLK_BYTES - 1] ^= 0x80;
 
         sha3_process_block72(ctx->state);
 
         /* Output */
-        memcpy(hashval, ctx->state, 64);
+        memcpy(resbuf, ctx->state, 64);
 }