Image Mode And The –Fill Option - Texas Instruments TMS320C54x User Manual

Image Mode and the –fill Option
10.8 Image Mode and the –fill Option
10.8.1 The –image Option
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This section points out the advantages of operating in image mode and
describes how to produce output files with a precise, continuous image of a
target memory range.
With the –image option, the utility generates a memory image by completely
filling all of the mapped ranges specified in the ROMS directive.
A COFF file consists of blocks of memory (sections) with assigned memory
locations. Typically, all sections are not adjacent: there are gaps between sec-
tions in the address space for which there is no data. When such a file is con-
verted without the use of image mode, the hex conversion utility bridges these
gaps by using the address records in the output file to skip ahead to the start
of the next section. In other words, there may be discontinuities in the output
file addresses. Some EPROM programmers do not support address disconti-
nuities.
In image mode, there are no discontinuities . Each output file contains a contin-
uous stream of data that corresponds exactly to an address range in target
memory. Any gaps before, between, or after sections are filled with a fill value
that you supply.
An output file converted by using image mode still has address records
because many of the hexadecimal formats require an address on each line.
However, in image mode, these addresses will always be contiguous.
Note: Defining the Ranges of Target Memory
If you use image mode, you must also use a ROMS directive. In image mode,
each output file corresponds directly to a range of target memory. You must
define the ranges. If you don't supply the ranges of target memory, the utility
tries to build a memory image of the entire target processor address space—
potentially a huge amount of output data. To prevent this situation, the utility
requires you to explicitly restrict the address space with the ROMS directive.