1 files changed, 102 insertions, 0 deletions
diff --git a/grub-core/lib/adler32.c b/grub-core/lib/adler32.c
new file mode 100644
index 0000000..43b68af
--- /dev/null
+++ b/grub-core/lib/adler32.c
@@ -0,0 +1,102 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2012  Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+#include <grub/dl.h>
+#include <grub/crypto.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+struct adler32_context
+{
+  grub_uint16_t a, b;
+  grub_uint32_t c;
+};
+
+static void
+adler32_init (void *context)
+{
+  struct adler32_context *ctx = context;
+
+  ctx->a = 1;
+  ctx->b = 0;
+}
+
+#define MOD 65521
+
+static grub_uint16_t
+mod_add (grub_uint16_t a, grub_uint16_t b)
+{
+  if ((grub_uint32_t) a + (grub_uint32_t) b >= MOD)
+    return a + b - MOD;
+  return a + b;
+}
+
+static void
+adler32_write (void *context, const void *inbuf, grub_size_t inlen)
+{
+  struct adler32_context *ctx = context;
+  const grub_uint8_t *ptr = inbuf;
+
+  while (inlen)
+    {
+      ctx->a = mod_add (ctx->a, *ptr);
+      ctx->b = mod_add (ctx->a, ctx->b);
+      inlen--;
+      ptr++;
+    }
+}
+
+static void
+adler32_final (void *context __attribute__ ((unused)))
+{
+}
+
+static grub_uint8_t *
+adler32_read (void *context)
+{
+  struct adler32_context *ctx = context;
+  if (ctx->a > MOD)
+    ctx->a -= MOD;
+  if (ctx->b > MOD)
+    ctx->b -= MOD;
+  ctx->c = grub_cpu_to_be32 (ctx->a | (ctx->b << 16));
+  return (grub_uint8_t *) &ctx->c;
+}
+
+static gcry_md_spec_t spec_adler32 =
+  {
+    "ADLER32", 0, 0, 0, 4,
+    adler32_init, adler32_write, adler32_final, adler32_read,
+    sizeof (struct adler32_context),
+#ifdef GRUB_UTIL
+    .modname = "adler32",
+#endif
+    .blocksize = 64
+  };
+
+
+GRUB_MOD_INIT(adler32)
+{
+  grub_md_register (&spec_adler32);
+}
+
+GRUB_MOD_FINI(adler32)
+{
+  grub_md_unregister (&spec_adler32);
+}