f8ea1e8e56
Keeping the base address of this structure in a register allows us to use offsets to load individual fields from it, without needing their individual addresses. However, the ldr instruction can only use immediate offsets relative to the low registers (r0-r7), or the stack pointer (r13). Low registers are in short supply and are needed for other instructions which can only use r0-r7, so we use the stack pointer here. It's safe to do this because we do not use the stack. There are no function calls, interrupt handlers or push/pop instructions in the M0 code. This change saves four cycles by eliminating loads of the addresses for the offset & tx registers, plus a further two by eliminating the need to stash one of these addresses in r8.
HackRF
This repository contains hardware designs and software for HackRF, a low cost, open source Software Defined Radio platform.
(photo by fd0 from https://github.com/fd0/hackrf-one-pictures)
principal author: Michael Ossmann mike@ossmann.com
Information on HackRF and purchasing HackRF: https://greatscottgadgets.com/hackrf/
Documentation
Documentation for HackRF can be viewed on Read the Docs. The raw documenation files for HackRF are in the docs folder in this repository and can be built locally by installing Sphinx Docs and running make html. Documentation changes can be submitted through pull request and suggestions can be made as GitHub issues.
Getting Help
Before asking for help with HackRF, check to see if your question is listed in the FAQ.
For assistance with HackRF general use or development, please look at the issues on the GitHub project. This is the preferred place to ask questions so that others may locate the answer to your question in the future.
We invite you to join our community discussions on Discord. Note that while technical support requests are welcome here, we do not have support staff on duty at all times. Be sure to also submit an issue on GitHub if you've found a bug or if you want to ensure that your request will be tracked and not overlooked.
If you wish to see past discussions and questions about HackRF, you may also view the mailing list archives.
GitHub issues on this repository that are labelled "technical support" by Great Scott Gadgets employees can expect a response time of two weeks. We currently do not have expected response times for other GitHub issues or pull requests for this repository.