<<<
|
<<<
|
:sectnums:
|
:sectnums:
|
==== Instruction Memory (IMEM)
|
==== Instruction Memory (IMEM)
|
|
|
[cols="<3,<3,<4"]
|
[cols="<3,<3,<4"]
|
[frame="topbot",grid="none"]
|
[frame="topbot",grid="none"]
|
|=======================
|
|=======================
|
| Hardware source file(s): | neorv32_imem.vhd |
|
| Hardware source file(s): | neorv32_imem.entity.vhd | entity-only definition
|
|
| | mem/neorv32_imem.default.vhd | default _platform-agnostic_ memory architecture
|
| Software driver file(s): | none | _implicitly used_
|
| Software driver file(s): | none | _implicitly used_
|
| Top entity port: | none |
|
| Top entity port: | none |
|
| Configuration generics: | _MEM_INT_IMEM_EN_ | implement processor-internal IMEM when _true_
|
| Configuration generics: | _MEM_INT_IMEM_EN_ | implement processor-internal IMEM when _true_
|
| | _MEM_INT_IMEM_SIZE_ | IMEM size in bytes
|
| | _MEM_INT_IMEM_SIZE_ | IMEM size in bytes
|
| | _INT_BOOTLOADER_EN_ | use internal bootlodaer when _true_ (implements IMEM as ROM)
|
| | _INT_BOOTLOADER_EN_ | use internal bootlodaer when _true_ (implements IMEM as _uninitialized_ RAM)
|
| CPU interrupts: | none |
|
| CPU interrupts: | none |
|
|=======================
|
|=======================
|
|
|
[NOTE]
|
[NOTE]
|
The default `neorv32_imem.vhd` HDL source file provides a _generic_ memory design that infers embedded
|
The actual IMEM is split into two design files: a plain entity definition (`neorv32_imem.entity.vhd`) and the actual
|
memory for _larger_ memory configurations. You might need to replace/modify the source file in order to use
|
architecture definition (`mem/neorv32_imem.default.vhd`). This **default architecture** provides a _generic_ and
|
platform-specific features (like advanced memory resources) or to improve technology mapping and/or timing.
|
_platform independent_ memory design that (should) infers embedded memory block. You can replace/modify the architecture
|
|
source file in order to use platform-specific features (like advanced memory resources) or to improve technology mapping
|
|
and/or timing.
|
|
|
Implementation of the processor-internal instruction memory is enabled via the processor's
|
Implementation of the processor-internal instruction memory is enabled via the processor's
|
_MEM_INT_IMEM_EN_ generic. The size in bytes is defined via the _MEM_INT_IMEM_SIZE_ generic. If the
|
_MEM_INT_IMEM_EN_ generic. The size in bytes is defined via the _MEM_INT_IMEM_SIZE_ generic. If the
|
IMEM is implemented, the memory is mapped into the instruction memory space and located right at the
|
IMEM is implemented, the memory is mapped into the instruction memory space and located right at the
|
beginning of the instruction memory space (default `ispace_base_c` = 0x00000000).
|
beginning of the instruction memory space (default `ispace_base_c` = 0x00000000).
|
|
|
By default, the IMEM is implemented as RAM, so the content can be modified during run time. This is
|
By default, the IMEM is implemented as RAM, so the content can be modified during run time. This is
|
required when using a bootloader that can update the content of the IMEM at any time. If you do not need
|
required when using a bootloader that can update the content of the IMEM at any time. If you do not need
|
the bootloader anymore – since your application development has completed and you want the program to
|
the bootloader anymore – since your application development has completed and you want the program to
|
permanently reside in the internal instruction memory – the IMEM is automatically implemented as _pre-intialized_
|
permanently reside in the internal instruction memory – the IMEM is automatically implemented as _pre-intialized_
|
ROM when the processor-internal bootloader is disabled (_INT_BOOTLOADER_EN_ = _false_).
|
ROM when the processor-internal bootloader is disabled (_INT_BOOTLOADER_EN_ = _false_).
|
|
|
When the IMEM is implemented as ROM, it will be initialized during synthesis with the actual application
|
When the IMEM is implemented as ROM, it will be initialized during synthesis with the actual application
|
program image. The compiler toolchain will generate a VHDL initialization
|
program image. The compiler toolchain will generate a VHDL initialization
|
file `rtl/core/neorv32_application_image.vhd`, which is automatically inserted into the IMEM. If
|
file `rtl/core/neorv32_application_image.vhd`, which is automatically inserted into the IMEM. If
|
the IMEM is implemented as RAM (default), the memory will **not be initialized** at all.
|
the IMEM is implemented as RAM (default), the memory will **not be initialized** at all.
|
|
|
