introduce new feature for the updater: UPDATECRC32

[pub/USBaspLoader.git] / updater / crccheck.c

diff --git a/updater/crccheck.c b/updater/crccheck.c
new file mode 100644 (file)
index 0000000..798c37a
--- /dev/null
+++ b/updater/crccheck.c
@@ -0,0 +1,36 @@
+/****************************************************************************/
+/* CRC32 stuff taken and adapted from lib_crc version 1.16 :                */
+/*   Library         : lib_crc                                              */
+/*   File            : lib_crc.c                                            */
+/*   Author          : Lammert Bies  1999-2008                              */
+/*   E-mail          : info@lammertbies.nl                                  */
+/****************************************************************************/
+
+/* the ATxmega series NVM CRC compatible polynom */
+/* on ATxmega you can do this much faster in hardware */
+#define                 P_32        0xEDB88320L
+#define                 D_32        0xFFFFFFFFL
+
+uint32_t crc_tab32_value(uint8_t address) {
+  uint32_t result;
+  uint8_t  j;
+
+  result = (uint32_t)address & 0xffL;
+  for (j=0; j<8; j++) {
+      if (result & 0x00000001L)        result = (result >> 1) ^ P_32;
+      else                     result = result >> 1;
+  }
+
+  return result;
+}
+
+uint32_t update_crc_32(uint32_t crc, uint8_t c) {
+  uint32_t tmp, long_c;
+
+  long_c = (uint32_t)c & 0xffL;
+
+  tmp = crc ^ long_c;
+  crc = (crc >> 8) ^ crc_tab32_value(tmp & 0xffL);
+
+  return crc;
+}