Jump to Content
Register Log in

RISCY BUSINESS
Blog
Forums
Episode Guide
twitter
We are currently in the process of converting the website to the new design. Some pages, like this one, are still broken. We appreciate your patience.
RISCY BUSINESS»Episode Guide
__wrap_write
References ▼
SiFive Forums
The Big RISCY BUSINESS Question Thread
[1]0:15[2]22:43
SiFive Developers
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
Filter mode:
Topics
hardware
(null topic)
Media
🗪Chat Comment
🖮Programming🟉
📖Research
🖌Whiteboard
🎭
🏟
🔗
Link to: current timestamp
Credits
Host
Neo Ar
Indexer
Matt Mascarenhas
?
?

Keyboard Navigation

Global Keys

[, < / ], > Jump to previous / next episode
W, K, P / S, J, N Jump to previous / next marker
t / T Toggle theatre / SUPERtheatre mode
V Revert filter to original state Y Select link (requires manual Ctrl-c)

Menu toggling

q Quotes r References f Filter y Link c Credits

In-Menu Movement

a
w
s
d
h j k l
←
↑
↓
→

Quotes and References Menus

Enter Jump to timecode

Quotes, References and Credits Menus

o Open URL (in new tab)

Filter Menu

x, Space Toggle category and focus next
X, ShiftSpace Toggle category and focus previous
v Invert topics / media as per focus

Filter and Link Menus

z Toggle filter / linking mode

Credits Menu

Enter Open URL (in new tab)
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
🗪
12:22riskyfive Google does log2
🗪
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
🗪
18:37riskyfive Yay for decimal
🗪
18:43Continue calculating the maximum ticks our proposed code would support
🖌
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