44 lines
3.1 KiB
Plaintext
44 lines
3.1 KiB
Plaintext
[video member=miotatsu stream_platform=twitch project=riscy title="uart_init, get_cpu_freq, & `static` Legalese" vod_platform=youtube id=HVxZkIliQd0 annotator=Miblo]
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[0:07][Recap and set the stage for the day]
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[2:30][Consult Table 7.1: HiFive1 GPIO Offset to Board Pin Number, and locate the definition of IOF0_UART0_MASK[ref
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site="SiFive Developers"
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page="SiFive HiFive1 Getting Started Guide"
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url=https://static.dev.sifive.com/dev-kits/hifive1/hifive1-getting-started-v1.0.3.pdf]][:hardware :research]
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[6:17][Return to uart_init() and determine to understand how IOF0_UART0_MASK is being used][:peripheral]
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[8:34][Refresh our memory on the GPIO Complex[ref
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site="SiFive Developers"
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page="Freedom E310-G000 Manual"
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url=https://www.sifive.com/documentation/chips/freedom-e310-g000-manual/] and HW I/O Functions (IOF)[ref
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site="SiFive Developers"
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page="Freedom E300 Platform Reference Manual"
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url=https://www.sifive.com/documentation/freedom-soc/freedom-e300-platform-reference-manual/]][:hardware :research]
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[10:49][Assume the layout of the IOF select register[ref
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site="SiFive Developers"
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page="SiFive HiFive1 Getting Started Guide"
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url=https://static.dev.sifive.com/dev-kits/hifive1/hifive1-getting-started-v1.0.3.pdf]][:hardware :research]
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[14:09][Consult the annotations for IOF[ref
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site=YouTube
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page="RISCY BUSINESS - Day 27: Diving Into Pulse Width Modulation"
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url=https://www.youtube.com/watch?v=wBy4tjKEF3s]]
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[17:44][Refresh our memory on the IOF masks for the LEDs][:peripheral]
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[21:38][Match up our IOF0_UART0_MASK in code with the documentation[ref
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site="SiFive Developers"
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page="SiFive HiFive1 Getting Started Guide"
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url=https://static.dev.sifive.com/dev-kits/hifive1/hifive1-getting-started-v1.0.3.pdf]][:peripheral :research]
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[25:23][Critique the clarity of using masks instead of offsets for UART0][:experience]
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[29:09][Consider what the static keyword does in terms of zero initialisation][:language]
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[41:36][Consult the C11 spec for the default initialisation rule of locally scoped static variables[ref
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title="ISO/IEC 9899:201x"
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url=http://open-std.org/JTC1/SC22/WG14/www/docs/n1570.pdf]][:language :research]
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[53:08][Read section 5.1.2 "Execution environments" in C11 spec, and determine to confirm with SiFive whether their static implementation does zero initialise[ref
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title="ISO/IEC 9899:201x"
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url=http://open-std.org/JTC1/SC22/WG14/www/docs/n1570.pdf]][:language :research]
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[56:56][Read about how the uninitialised .bss segment in Linux executables, which holds global and static variables, initialises variables to zero][:platform :research]
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[57:59][Recommend not explicitly initialising static and global variables to 0 to save some space][:language :platform :trivia]
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[59:04][Ask in the forums where it is defined how uninitialised variables with static storage duration are initialized for the HiFive1[ref
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site="SiFive Forums"
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page="The Big RISCY BUSINESS Question Thread"
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url=https://forums.sifive.com/t/the-big-riscy-business-question-thread/531/4]][:platform :research]
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[1:05:18][We are out of time for tonight]
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[/video]
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