Mark BBBuffer as #[repr(C)] to support alignment #93
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Some DMA engines and peripherals require that buffers are precisely aligned. This commit marks BBBuffer as #[repr(C)] so that the buffer is the first member of the struct. With this guarantee, we can align the BBBuffer for our hardware-assisted transfers. Updated documentation shows one way to align the buffer. Tested on an i.MX RT processor, where the DMA engine requires circular buffers that are power-of-two sized and aligned. If I can't align my BBBuffer, I'll treat the BBBuffer as linear memory and schedule multiple transfers to handle split_read wraparound. I'm happy to go this route if this commit isn't appropriate for bbqueue.
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Some DMA engines and peripherals require that buffers are precisely
aligned. This commit marks BBBuffer as #[repr(C)] so that the buffer is
the first member of the struct. With this guarantee, we can align the
BBBuffer for our hardware-assisted transfers. Updated documentation
shows one way to align the buffer.
Tested on an i.MX RT processor, where the DMA engine requires circular
buffers that are power-of-two sized and aligned. If I can't align my
BBBuffer, I'll treat the BBBuffer as linear memory and schedule multiple
transfers to handle split_read wraparound. I'm happy to go this route if
this commit isn't appropriate for bbqueue.