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RISCY BUSINESS»Episode Guide
__wrap_write
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The Big RISCY BUSINESS Question Thread
[1]0:15[2]22:43
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Freedom E300 Platform Reference Manual
[3]27:50[4]32:42
Wikipedia
Universal asynchronous receiver/​transmitter
[5]34:00[6]37:52
GitHub
stb/​stb_sprintf.h
[7]47:04
RISC-V
Draft Privileged ISA Specification v1.9.1
[8]51:32
RISC-V
User-Level ISA Specification v2.1
[9]51:32
SiFive Developers
E3 Coreplex Manual
[10]51:32
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0:00Recap and set the stage for the day
0:00Recap and set the stage for the day
0:00Recap and set the stage for the day
0:15Consult Bruce's reply regarding the measure_cpu_freq() computation1
0:15Consult Bruce's reply regarding the measure_cpu_freq() computation1
0:15Consult Bruce's reply regarding the measure_cpu_freq() computation1
1:47riskyfive Hey
🗪
1:47riskyfive Hey
🗪
1:47riskyfive Hey
🗪
1:53Determine to figure out how we could force measure_cpu_freq() to cause an integer overflow
1:53Determine to figure out how we could force measure_cpu_freq() to cause an integer overflow
1:53Determine to figure out how we could force measure_cpu_freq() to cause an integer overflow
5:21Calculating the maximum value of delta_mcycle
🖌
5:21Calculating the maximum value of delta_mcycle
🖌
5:21Calculating the maximum value of delta_mcycle
🖌
5:51riskyfive 32768 is a power of 2, so just subtract log2(32768) bits from 32 bits?
🗪
5:51riskyfive 32768 is a power of 2, so just subtract log2(32768) bits from 32 bits?
🗪
5:51riskyfive 32768 is a power of 2, so just subtract log2(32768) bits from 32 bits?
🗪
6:18Continuing that maximum delta_mcycle calculation
🖌
6:18Continuing that maximum delta_mcycle calculation
🖌
6:18Continuing that maximum delta_mcycle calculation
🖌
6:45riskyfive log2(x) is how many bits are needed to represent x
🗪
6:45riskyfive log2(x) is how many bits are needed to represent x
🗪
6:45riskyfive log2(x) is how many bits are needed to represent x
🗪
7:06Continuing that maximum delta_mcycle calculation
7:06Continuing that maximum delta_mcycle calculation
7:06Continuing that maximum delta_mcycle calculation
9:56riskyfive Notice that 131072 is also a power of two
🗪
9:56riskyfive Notice that 131072 is also a power of two
🗪
9:56riskyfive Notice that 131072 is also a power of two
🗪
10:06Convert our calculated value to hex
10:06Convert our calculated value to hex
10:06Convert our calculated value to hex
12:22riskyfive Google does log2
🗪
12:22riskyfive Google does log2
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12:22riskyfive Google does log2
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12:34Perform log2 on our hex value, and then try RiskyFive's original computation
12:34Perform log2 on our hex value, and then try RiskyFive's original computation
12:34Perform log2 on our hex value, and then try RiskyFive's original computation
15:26Calculating the maximum number of ticks we can support
🖌
15:26Calculating the maximum number of ticks we can support
🖌
15:26Calculating the maximum number of ticks we can support
🖌
17:25riskyfive If your max representation is 10,000,000, and you are thinking how many times you can fit 1000, you just subtract log10(1000)=3 from log10(10,000,000)=7; 7-3=4; 10^4 = 10,000. You can fit 1000 10,000 times in 10,000,000
🗪
17:25riskyfive If your max representation is 10,000,000, and you are thinking how many times you can fit 1000, you just subtract log10(1000)=3 from log10(10,000,000)=7; 7-3=4; 10^4 = 10,000. You can fit 1000 10,000 times in 10,000,000
🗪
17:25riskyfive If your max representation is 10,000,000, and you are thinking how many times you can fit 1000, you just subtract log10(1000)=3 from log10(10,000,000)=7; 7-3=4; 10^4 = 10,000. You can fit 1000 10,000 times in 10,000,000
🗪
18:37riskyfive Yay for decimal
🗪
18:37riskyfive Yay for decimal
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18:37riskyfive Yay for decimal
🗪
18:43Continue calculating the maximum ticks our proposed code would support
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18:43Continue calculating the maximum ticks our proposed code would support
🖌
18:43Continue calculating the maximum ticks our proposed code would support
🖌
22:43Reflect on the relative robustness of the official code, and give Bruce a like2
22:43Reflect on the relative robustness of the official code, and give Bruce a like2
22:43Reflect on the relative robustness of the official code, and give Bruce a like2
23:38Continue studying __wrap_write()
23:38Continue studying __wrap_write()
23:38Continue studying __wrap_write()
27:50Study the loops in __wrap_write(), in conjunction with the Transmit Data Register documentation3
27:50Study the loops in __wrap_write(), in conjunction with the Transmit Data Register documentation3
27:50Study the loops in __wrap_write(), in conjunction with the Transmit Data Register documentation3
32:42Marry up the defined UART_REG_TXFIFO with the documentation4 and determine that we fully understand write
32:42Marry up the defined UART_REG_TXFIFO with the documentation4 and determine that we fully understand write
32:42Marry up the defined UART_REG_TXFIFO with the documentation4 and determine that we fully understand write
34:00Research if there is a new line standard for UART5
📖
34:00Research if there is a new line standard for UART5
📖
34:00Research if there is a new line standard for UART5
📖
36:18riskyfive The concept of new lines is not defined at the UART level
🗪
36:18riskyfive The concept of new lines is not defined at the UART level
🗪
36:18riskyfive The concept of new lines is not defined at the UART level
🗪
36:48riskyfive It's higher level. They probably use CR LF because many terminals (Putty, etc.) use that by default
🗪
36:48riskyfive It's higher level. They probably use CR LF because many terminals (Putty, etc.) use that by default
🗪
36:48riskyfive It's higher level. They probably use CR LF because many terminals (Putty, etc.) use that by default
🗪
37:52Read about UART Data framing6
📖
37:52Read about UART Data framing6
📖
37:52Read about UART Data framing6
📖
40:12riskyfive In my FPGA app I just sent \n [sic] without doing that conversion. Then I changed the Putty config when I used it with Windows
🗪
40:12riskyfive In my FPGA app I just sent \n [sic] without doing that conversion. Then I changed the Putty config when I used it with Windows
🗪
40:12riskyfive In my FPGA app I just sent \n [sic] without doing that conversion. Then I changed the Putty config when I used it with Windows
🗪
40:49riskyfive I just sent slash n, it doesn't print \ n here
🗪
40:49riskyfive I just sent slash n, it doesn't print \ n here
🗪
40:49riskyfive I just sent slash n, it doesn't print \ n here
🗪
41:45Research multiple stop bits in UART
📖
41:45Research multiple stop bits in UART
📖
41:45Research multiple stop bits in UART
📖
44:27riskyfive I think two stop bits also helps resynchronization
🗪
44:27riskyfive I think two stop bits also helps resynchronization
🗪
44:27riskyfive I think two stop bits also helps resynchronization
🗪
44:54riskyfive If you open your serial terminal at mid-transmission what can happen is that you start decoding what you think is a start bit but it's actually data. After that you may never recover unless you have more than one stop bits
🗪
44:54riskyfive If you open your serial terminal at mid-transmission what can happen is that you start decoding what you think is a start bit but it's actually data. After that you may never recover unless you have more than one stop bits
🗪
44:54riskyfive If you open your serial terminal at mid-transmission what can happen is that you start decoding what you think is a start bit but it's actually data. After that you may never recover unless you have more than one stop bits
🗪
47:04Shout out to Sean T. Barrett's publication of Jeff Roberts' printf7
47:04Shout out to Sean T. Barrett's publication of Jeff Roberts' printf7
47:04Shout out to Sean T. Barrett's publication of Jeff Roberts' printf7
48:40Consult our TODO list
🖌
48:40Consult our TODO list
🖌
48:40Consult our TODO list
🖌
49:38Consider checking out the other demos
49:38Consider checking out the other demos
49:38Consider checking out the other demos
51:32Plan what to study from the table of contents in the Privileged ISA Specification,8 note that the User-Level ISA Specification9 will be more of a reference source for us, and plan what's left from the E3 Coreplex Manual10
51:32Plan what to study from the table of contents in the Privileged ISA Specification,8 note that the User-Level ISA Specification9 will be more of a reference source for us, and plan what's left from the E3 Coreplex Manual10
51:32Plan what to study from the table of contents in the Privileged ISA Specification,8 note that the User-Level ISA Specification9 will be more of a reference source for us, and plan what's left from the E3 Coreplex Manual10
56:26Scan through led_fade.c to determine that we understand everything in it
📖
56:26Scan through led_fade.c to determine that we understand everything in it
📖
56:26Scan through led_fade.c to determine that we understand everything in it
📖
1:02:01Plan
🖌
1:02:01Plan
🖌
1:02:01Plan
🖌
1:03:21We're done for today
1:03:21We're done for today
1:03:21We're done for today