24 lines
1.6 KiB
Plaintext
24 lines
1.6 KiB
Plaintext
[video member=miotatsu stream_platform=twitch project=riscy title="Understanding Center Aligned Waveforms & Searching For __atomic_fetch_xor" vod_platform=youtube id=aXPgZGqmYYE annotator=Miblo]
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[0:07][Recap and set the stage for the day]
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[1:00][Shifting << 1 in order to produce a centre-aligned waveform][:blackboard]
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[3:35][Try setting G to 0x8000, centre-aligned][:peripheral]
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[5:02][:Run the program and see a light, to determine that the value gets inverted at 0x8000]
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[5:37][Try setting G to 0x7FFF and :run to see it lit, but a little dimmer]
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[7:23][Determine that the code is shifting the wrong way, and change it to shift right]
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[8:53][:Run the program, and see that the brightness is uniform]
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[10:16][Determine that we fully understand PWM, and to review demo_gpio.c][:peripheral]
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[11:17][Review demo_gpio.c]
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[12:47][Note that we don't understand bit-banging, or know about atomic_fetch_xor_explicit()]
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[16:24][Consult the documentation for atomic_fetch_xor_explicit[ref
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site=cppreference.com
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page="atomic_fetch_xor, atomic_fetch_xor_explicit"
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url=http://en.cppreference.com/w/c/atomic/atomic_fetch_xor]][:memory :research]
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[19:02][Look into how we call atomic_fetch_xor_explicit() and read about memory_order[ref
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site=cppreference.com
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page=memory_order
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url=http://en.cppreference.com/w/c/atomic/memory_order]][:memory :research]
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[31:24][Hunt the Freedom E SDK for our atomic_fetch_xor_explicit()][:memory :research]
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[1:03:22][Hunt the GCC source for the __atomic_fetch_xor() built-in][:memory :research]
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[1:08:28][We are out of time for today, with the determination to continue investigating this]
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[/video]
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