mi4: replace chksum_crc32 with crc_32r

This uses an equivalent algorithm but with a different initial value
than we normally use (all bits off vs all bits on). Use the new crc_32r
to replace the original MI4 crc32 implementation.

This frees up some extra space on mi4 targets which gives us more
room on a few very space constrained targets (sansa c200/e200, etc).

Change-Id: Iaaac3ae353b30566156b1404cbf31ca32926203d

Author: James Buren

bootloader/fat32format.c

@@ -44,7 +44,6 @@
 #include "storage.h"
 #include "button.h"
 #include "disk.h"
-#include "crc32-mi4.h"
 #include <string.h>
 #include "i2c.h"
 #include "backlight-target.h"

bootloader/main-e200r-installer.c

@@ -35,7 +35,7 @@
 #include "file.h"
 #include "button.h"
 #include "disk.h"
-#include "crc32-mi4.h"
+#include "crc32.h"
 #include <string.h>
 #include "i2c.h"
 #include "backlight-target.h"
@@ -138,7 +138,7 @@ void* main(void)
 
     storage_read_sectors(pinfo.start + START_SECTOR_OF_ROM + ROMSECTOR_TO_HACK,
                          1 , sector);
-    crc32 = chksum_crc32 (sector, 512);
+    crc32 = crc_32r (sector, 512, 0);
 
 #if 0 /* not needed in release builds */
     printf("--- Hack Status ---");

bootloader/main-pp.c

@@ -37,7 +37,7 @@
 #include "adc.h"
 #include "button.h"
 #include "disk.h"
-#include "crc32-mi4.h"
+#include "crc32.h"
 #include "mi4-loader.h"
 #include "loader_strerror.h"
 #include <string.h>
@@ -169,7 +169,7 @@ int load_mi4_part(unsigned char* buf, struct partinfo* pinfo,
                         (mi4header.mi4size-MI4_HEADER_SIZE)/512, buf);
 
     /* Check CRC32 to see if we have a valid file */
-    sum = chksum_crc32 (buf,mi4header.mi4size-MI4_HEADER_SIZE);
+    sum = crc_32r (buf,mi4header.mi4size-MI4_HEADER_SIZE,0);
 
     printf("Calculated CRC32: %x", sum);
 

firmware/SOURCES

@@ -242,9 +242,6 @@ common/crc32.c
 #ifdef MODEL_NUMBER
 common/loader_strerror.c
 #endif
-#ifdef MI4_FORMAT
-common/crc32-mi4.c
-#endif
 #ifdef RKW_FORMAT
 common/crc32-rkw.c
 #endif

firmware/common/crc32-mi4.c

@@ -40,7 +40,6 @@
 
 #include "loader_strerror.h"
 #if defined(MI4_FORMAT)
-#include "crc32-mi4.h"
 #include "mi4-loader.h"
 #if defined(HAVE_BOOTDATA) && !defined(SIMULATOR)
 #include "bootdata.h"

firmware/include/crc32-mi4.h

@@ -27,12 +27,11 @@
 #include "config.h"
 #include "mi4-loader.h"
 #include "loader_strerror.h"
-#include "crc32-mi4.h"
+#include "crc32.h"
 #include "file.h"
 #if defined(HAVE_BOOTDATA)
 #include "system.h"
 #include "bootdata.h"
-#include "crc32.h"
 
 /* Write bootdata into location in FIRMWARE marked by magic header
  * Assumes buffer is already loaded with the firmware image
@@ -293,7 +292,7 @@ static int load_mi4_filename(unsigned char* buf,
         return EREAD_IMAGE_FAILED;
 
     /* Check CRC32 to see if we have a valid file */
-    sum = chksum_crc32 (buf, mi4header.mi4size - MI4_HEADER_SIZE);
+    sum = crc_32r (buf, mi4header.mi4size - MI4_HEADER_SIZE, 0);
 
     if(sum != mi4header.crc32)
         return EBAD_CHKSUM;