capi: Expose frame buffer API #94
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Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
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Since we hit a cursed Rust -> C ABI issues, I'm attaching a simple test program and files that triggers the madness, at @Luni-4's request. |
| /// Returns the correct `ssim` value or `NULL` on errors | ||
| #[no_mangle] | ||
| pub unsafe extern fn avm_calculate_frame_buf_ssim( | ||
| frame1: [*const u8; 3], |
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What cbindgen produces for those?
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It produces exactly the API I wanted:
/**
* Calculate the `msssim` metric between two frame buffers
*
* Returns the correct `msssim` value or `NULL` on errors
*/
const AVMContext *avm_calculate_frame_buf_msssim(const uint8_t *frame1[3],
ptrdiff_t frame1_strides[3],
const uint8_t *frame2[3],
ptrdiff_t frame2_strides[3],
uint32_t width,
uint32_t height,
uint8_t bitdepth,
AVMChromaSamplePosition chroma_pos,
AVMChromaSampling subsampling,
AVMRational pixel_aspect_ratio);But it doesn't matter, since Rust can't generate a confirming C ABI for it, as discussed on IRC.
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This is a bug in cbindgen. ptrdiff_t frame2_strides[3] is *mut frame2_strides.
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What would be the correct way to write the rust declaration to generate ptrdiff_t frame2_strides[3]? And should we file a cbindgen bug?
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Let me poke upstream to rustc confirm, but from what you are telling me it seems so and a good idea to tell cbindgen upstream.
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improper_ctypes is on by default only in extern blocks.
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improper_ctypes is on by default only in extern blocks.
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I mean... not's not really a good answer. Why wouldn't it be on for all extern "C" functions? It makes it almost useless.
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That's what I had been told today :) I hadn't tested it yet btw.
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upstream cbindgen would welcome a patch to prevent this and one to add annotations to use the style you'd use here.
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Now that C-APIs have been removed, are you still interested in re-adding them @dwbuiten? Or can we close this PR? |
Notes
Currently untested - I will get to testing this tonight after dinner, and will update the PR text after. It's very likely to explode on 4:0:0.
Comments welcome - it's kinda ugly, but such is C interop.
Also of note is that
Cargo.tomlin the main directory is sitll pointing to av-metrics 0.4.0 for some reason.