Emerson MVME7100 사용자 설명서

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);

}

The image flags of the header define various bit options that control how the image will be 
executed.

z

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.

z

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.

ImageOffset

unsigned integer

1

Offset from header start to entry

ImageFlags

unsigned integer

1

Refer to 

 

on page 95

ImageVersion

unsigned integer

1

User defined

Reserved

unsigned integer

8

Reserved for expansion

COPY_TO_RAM

0x00000001

Copy image to RAM at ImageRamAddress before execution

IMAGE_MCG

0x00000002

Alternate MOTLoad image

IMAGE_POST

0x00000004

POST image

DONT_AUTO_RUN

0x00000008

Image not to be executed