From 30ba68cb7eb8f662d7728f3b8d26a3933859ff5a Mon Sep 17 00:00:00 2001
From: Michael Snyder <msnyder@vmware.com>
Date: Tue, 23 Mar 2010 22:43:50 +0000
Subject: [PATCH] 2010-03-23  Michael Snyder  <msnyder@vmware.com>

	* server.c (crc32): New function.
	(handle_query): Add handling for 'qCRC:' request.
---
 gdb/gdbserver/ChangeLog |  5 +++
 gdb/gdbserver/server.c  | 68 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 73 insertions(+)

diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 552c83d5ee..cab5a73a70 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,8 @@
+2010-03-23  Michael Snyder  <msnyder@vmware.com>
+
+	* server.c (crc32): New function.
+	(handle_query): Add handling for 'qCRC:' request.
+
 2010-03-23  Pedro Alves  <pedro@codesourcery.com>
 
 	* linux-x86-low.c (x86_linux_prepare_to_resume): Clear DR6 if the
diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index a03f8774cd..05a41bfd9d 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -788,6 +788,47 @@ handle_threads_qxfer (const char *annex,
 
 }
 
+/* Table used by the crc32 function to calcuate the checksum.  */
+
+static unsigned int crc32_table[256] =
+{0, 0};
+
+/* Compute 32 bit CRC from inferior memory.
+
+   On success, return 32 bit CRC.
+   On failure, return (unsigned long long) -1.  */
+
+static unsigned long long
+crc32 (CORE_ADDR base, int len, unsigned int crc)
+{
+  if (!crc32_table[1])
+    {
+      /* Initialize the CRC table and the decoding table.  */
+      int i, j;
+      unsigned int c;
+
+      for (i = 0; i < 256; i++)
+	{
+	  for (c = i << 24, j = 8; j > 0; --j)
+	    c = c & 0x80000000 ? (c << 1) ^ 0x04c11db7 : (c << 1);
+	  crc32_table[i] = c;
+	}
+    }
+
+  while (len--)
+    {
+      unsigned char byte = 0;
+
+      /* Return failure if memory read fails.  */
+      if (read_inferior_memory (base, &byte, 1) != 0)
+	return (unsigned long long) -1;
+
+      crc = (crc << 8) ^ crc32_table[((crc >> 24) ^ byte) & 255];
+      base++;
+    }
+  return (unsigned long long) crc;
+}
+
 /* Handle all of the extended 'q' packets.  */
 void
 handle_query (char *own_buf, int packet_len, int *new_packet_len_p)
@@ -1421,6 +1462,33 @@ handle_query (char *own_buf, int packet_len, int *new_packet_len_p)
       return;
     }
 
+  if (strncmp ("qCRC:", own_buf, 5) == 0)
+    {
+      /* CRC check (compare-section).  */
+      char *comma;
+      CORE_ADDR base;
+      int len;
+      unsigned long long crc;
+
+      require_running (own_buf);
+      base == strtoul (own_buf + 5, &comma, 16);
+      if (*comma++ != ',')
+	{
+	  write_enn (own_buf);
+	  return;
+	}
+      len = strtoul (comma, NULL, 16);
+      crc = crc32 (base, len, 0xffffffff);
+      /* Check for memory failure.  */
+      if (crc == (unsigned long long) -1)
+	{
+	  write_enn (own_buf);
+	  return;
+	}
+      sprintf (own_buf, "C%lx", (unsigned long) crc);
+      return;
+    }
+
   /* Otherwise we didn't know what packet it was.  Say we didn't
      understand it.  */
   own_buf[0] = 0;