Checksum Algorithm; Image Flags; Table 6-2 Motload Image Flags - SMART Embedded Computing MVME7100ET Installation And Use Manual

6.7.1

Checksum Algorithm

The checksum algorithm is a simple unsigned word add of each word (4 byte) location in
the image. The image must be a multiple of 4 bytes in length (word-aligned). The content
of the checksum location in the header is not part of the checksum calculation. The
calculation assumes the location to be zero. The algorithm is implemented using the
following code:
Unsigned int checksum(
Unsigned int *startPtr,/* starting address */
Unsigned int endPtr/* ending address */
) {
unsigned int checksum=0;
while (startPtr < endPtr) {
checksum += *startPtr;
startPtr++;
}
return(checksum);
}
6.7.2

Image Flags

The image flags of the header define various bit options that control how the image will be
executed.
Table 6-2
Name
COPY_TO_RAM
IMAGE_MCG
IMAGE_POST
DONT_AUTO_RUN
COPY_TO_RAM
If set, this flag indicates that the image is to be copied to RAM at the address specified in
the header before control is passed. If not set, the image will be executed in flash. In both
instances, control will be passed at the image offset specified in the header from the base
of the image.
IMAGE_MCG
If set, this flag defines the image as being an Alternate MOTLoad, as opposed to USER,
image. This bit should not be set by developers of alternate boot images.
MVME7100ET Single Board Computer Installation and Use (6806800K87G)
MOTLoad Image Flags
Value
0x00000001
0x00000002
0x00000004
0x00000008
Interpretation
Copy image to RAM at ImageRamAddress before
execution
Alternate MOTLoad image
POST image
Image not to be executed
MOTLoad Firmware
101