Analog Devices VISUALDSP++ 3.5, Руководство пользователя

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Vi+ 3.5 Loader Manual 1-7
for 16-Bit Processors
Introduction
In this context, a boot-loadable file is a file that stores instruction code in
a formatted manner in order to be processed by a boot kernel. A
non-bootable file stores raw instruction code. Note that in some case, a
single file may contain both types of data.
Boot Kernels
A (loader) boot kernel refers to the resident program in the boot ROM
space responsible for booting the processor. Alternatively (or in absence of
the boot ROM), the boot kernel can be pre-loaded from the boot source
by a boot-strapping scheme.
When a reset signal is sent to the processor, the processor starts booting
from a PROM, host device, or through a communication port. For exam-
ple, a ADSP-218x/219x processor brings a 256-word program in internal
memory for execution. This small program is called a boot kernel. The
boot kernel then brings the rest of the booting routines into the proces-
sor’s memory. Finally, the boot kernel overwrites itself with the final block
and jumps to the beginning of the application program.
On the ADSP-219x DSPs, the highest 16 locations in page 0 program
memory and the highest 272 locations in page 0 data memory are reserved
for use by the ROM boot routines (typically for setting up DMA data
structures and for bookkeeping operations). Ensure that the boot sequence
entry code or boot-loaded program do not need to initialize this space at
boot time. However, the program can use these locations at run-time.
Some of the newer Blackfin processors (ADSP-BF531, ADSP-BF532, and
ADSP-BF533) do not require a boot kernel: the advanced on-chip boot
ROM allows the entire application program body to be booted into the
internal memory of the processor. The on-chip boot ROM for the former
processors behaves similar to the second-stage loader of ADSP-BF535 pro-
cessors. The boot ROM has the capability to parse address and count
information for each bootable block.