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by DavidS
Thu May 23, 2019 9:35 pm
Forum: Bare metal, Assembly language
Topic: A little Progress on my little OS Project:
Replies: 23
Views: 1408

Re: A little Progress on my little OS Project:

Mysterious blessings: Maybe it is just a random blessing that I am having trouble uploading to GitHub today. I just tryed the updated code on the ARMv8 based RPi 3B and it failed do to not recognizing the SETEND instruction. I am not sure why this would not work in AARCH32 on the ARMv8 used in the R...
by DavidS
Thu May 23, 2019 2:49 pm
Forum: Bare metal, Assembly language
Topic: A little Progress on my little OS Project:
Replies: 23
Views: 1408

Re: A little Progress on my little OS Project:

Another Update:
I am able to edit the readme.md and wiki pages now on github. Still having trouble uploading will let it be known when I manage to get that bit going.
by DavidS
Thu May 23, 2019 1:58 pm
Forum: Bare metal, Assembly language
Topic: A little Progress on my little OS Project:
Replies: 23
Views: 1408

Re: A little Progress on my little OS Project:

Sounds awesome. What's the link to your repository on github? The link is: https://github.com/ARMDavid/ArmTOS NOTE: As I have not been able to update that, the info is wrong. I am not using a CPU emulator at all (yet), everything is ARMv7 native and the OS is a new TOS API compatible OS (Big Endian...
by DavidS
Thu May 23, 2019 12:45 pm
Forum: Bare metal, Assembly language
Topic: A little Progress on my little OS Project:
Replies: 23
Views: 1408

Re: A little Progress on my little OS Project:

I like the simpler OpenVG, mainly because I don't understand OpenGL yet ;) Getting the GUI working convinced me I need the rest of an real OS. No one has told me they own Punk OS yet ;) Sounds like you are much further along than most of us. I've been distracted by seeing if I can have AI/NN built ...
by DavidS
Thu May 23, 2019 3:00 am
Forum: Bare metal, Assembly language
Topic: A little Progress on my little OS Project:
Replies: 23
Views: 1408

A little Progress on my little OS Project:

I have managed to get far enough to do some of the development self hosted. The spec largely is modeled after what is already posted at github, though I can not seem to make any updates or uploads there, sorry about that issue. I will be updating the github wiki for this project as soon as I can, an...
by DavidS
Tue May 21, 2019 4:58 am
Forum: Bare metal, Assembly language
Topic: Puzzled, Mem speed?
Replies: 31
Views: 2540

Re: Puzzled, Mem speed?

It is interesting how people have pointed out issues with using a single instruction pair for memcopy . I think we all know these. The test case example (and the kind of thing that would be done this way), is for a memset operation using a single STMIA instruction in the inner loop (no load operatio...
by DavidS
Tue Mar 19, 2019 10:49 am
Forum: Other projects
Topic: Using an RPi to reduce Power Usage, Off Grid.
Replies: 8
Views: 613

Re: Using an RPi to reduce Power Usage, Off Grid.

If anyone has any suggestions on things that can be done to improve on what I am doing, please give them. As I understand it, an original B+ will draw about half the current of an original B, so might be worth moving to one of those. Valid point. Unfortunately I only have two B+ boards at the momen...
by DavidS
Tue Mar 19, 2019 10:43 am
Forum: Bare metal, Assembly language
Topic: Puzzled, Mem speed?
Replies: 31
Views: 2540

Re: Puzzled, Mem speed?

The reason being that these units could be put to other uses while the memcopy is being completed by DMA, and I do not know of many personal computers that are without DMA. I don't think moving stuff between memory and registers with LDM or LDP or LDR can use DMA ? Or is this an ARM thing I don't k...
by DavidS
Tue Mar 19, 2019 10:35 am
Forum: Other projects
Topic: Using an RPi to reduce Power Usage, Off Grid.
Replies: 8
Views: 613

Using an RPi to reduce Power Usage, Off Grid.

It took me some time to get down to 2.0KW/h per day power consumption using traditional methods of usage timing, and careful selection of devices that consume power. Now I am working on using an old Raspberry Pi Model B (original 2012 model with full sized SD-Card) with a serial attached Arduino Meg...
by DavidS
Tue Mar 19, 2019 10:05 am
Forum: Bare metal, Assembly language
Topic: Puzzled, Mem speed?
Replies: 31
Views: 2540

Re: Puzzled, Mem speed?

Hi, I am using the ARM STM instruction in a loop that I have verified to be the fastest possible, storing 4 registers per store (any more or less slows us down). Only one store per iteration of the loop (any more slows us down). This seems odd. Here I've linked more memcpy implementations, but all ...
by DavidS
Sun Mar 17, 2019 4:06 pm
Forum: Bare metal, Assembly language
Topic: How to use gpio clock
Replies: 4
Views: 845

Re: How to use gpio clock

That depends on how you are setting up the PWM registers. Could we have your assembler for the PWM registers? .section .init .globl _start _start: b main .section .text main: mov sp,#0x8000 /*Configure GPIO18 as PWM0 output, which is ALT Fun 5 setting in the register 10b=2 decimal*/ mov r0,#18 mov ...
by DavidS
Sun Mar 17, 2019 3:40 pm
Forum: Graphics programming
Topic: SPi Display Questions?
Replies: 22
Views: 2203

Re: SPi Display Questions?

Is there a path from the GPU to HDMI if you do GPU assembly language like Herman Hermitageet Al? I'd possibly rather learn that than OpenGL https://github.com/hermanhermitage But yeah, I don't know how it's plumbed. Could be swithable from HDMI to SPI or not, but bit-banging with the CPU mostly jus...
by DavidS
Sun Mar 17, 2019 3:09 pm
Forum: Graphics programming
Topic: SPi Display Questions?
Replies: 22
Views: 2203

Re: SPi Display Questions?

Double post, forum issue well known. Removed redundant repeat post text.
by DavidS
Sun Mar 17, 2019 2:57 pm
Forum: Graphics programming
Topic: SPi Display Questions?
Replies: 22
Views: 2203

Re: SPi Display Questions?

16bpp is the default depth for Raspbian framebuffer and X, so it is enough for 99% of all applications. The framebuffer used to default to 16bpp but I'm sure it's been 32bpp for ages (couple of years or more). I was pleasantly surprised when I wrote this https://sourceforge.net/projects/fbgrad/ but...
by DavidS
Sun Mar 17, 2019 4:00 am
Forum: Graphics programming
Topic: SPi Display Questions?
Replies: 22
Views: 2203

Re: SPi Display Questions?

Thank you for that information. I understand that the refresh is a bit low if you do not overclock the SPI, and that depends on the controller.

16bpp is the default depth for Raspbian framebuffer and X, so it is enough for 99% of all applications.
by DavidS
Sat Mar 16, 2019 9:20 am
Forum: Graphics programming
Topic: SPi Display Questions?
Replies: 22
Views: 2203

Re: SPi Display Questions?

It apears that people are managing to get some good results with these displays in Linux. Still not seeing any information on directly playing with these, other than the datasheets. As the potential results are fairly good I guess I will have to order one and play with it, see what I can get it to d...
by DavidS
Sat Mar 16, 2019 3:15 am
Forum: Other
Topic: Anyone Know Status on RPi Native AROS?
Replies: 9
Views: 5023

Re: Anyone Know Status on RPi Native AROS?

Would be great, but its been "coming soon" for a long time now... I wonder if it will ever get over that line :? Look at his blog. It looks like it realy is coming soon. Already have working USB (largely), to a usable state anyway, Already running correctly in Big Endian mode, already implementing ...
by DavidS
Sat Mar 16, 2019 3:10 am
Forum: Bare metal, Assembly language
Topic: Puzzled, Mem speed?
Replies: 31
Views: 2540

Re: Puzzled, Mem speed?

3 to 4 fold is pretty much what the data sheet says which proves it isn't a data bus issue but a CPU cycle latency issue and you don't have enough speed on the ARM to max the bus out. BTW: STRD is slower on the RPi 1, and faster on the RPi 2B, 3B, and 3B+ (my 2B is a BCM2856 ARMv7 version). Though ...
by DavidS
Sat Mar 16, 2019 2:37 am
Forum: Bare metal, Assembly language
Topic: Puzzled, Mem speed?
Replies: 31
Views: 2540

Re: Puzzled, Mem speed?

3 to 4 fold is pretty much what the data sheet says which proves it isn't a data bus issue but a CPU cycle latency issue and you don't have enough speed on the ARM to max the bus out. WTB faster ARM :-) If you want to test data bus speed probably setup same sort of thing from the VC4 that only writ...
by DavidS
Fri Mar 15, 2019 10:11 pm
Forum: Bare metal, Assembly language
Topic: Puzzled, Mem speed?
Replies: 31
Views: 2540

Re: Puzzled, Mem speed?

here is my entry doing 64 bit writes .. if the ARM7 timings are close it is a lot quicker r0 = low 32 bits of 64 bits value to write r1 = high 32 bits of 64 bit value to write r2 = frame buffer end address to end write at r3 = frame buffer start address to start write at movt r3, 0 movt r2, 0 .loop...
by DavidS
Fri Mar 15, 2019 10:04 pm
Forum: Bare metal, Assembly language
Topic: Puzzled, Mem speed?
Replies: 31
Views: 2540

Re: Puzzled, Mem speed?

jahboater wrote:
Fri Mar 15, 2019 4:42 pm
Perhaps put the SUBS before the STMEA, then there is more time for the flags to be set before the BPL?

Code: Select all

.ClrSLpX
      SUBS  R6,R6,#4
      STMEA R7!,{R0-R3}
      BPL ClrSLpX
Thank you. Face palm moment, I did what I recomend against for performance. Speed up not significant though.
by DavidS
Fri Mar 15, 2019 4:15 pm
Forum: Graphics programming
Topic: SPi Display Questions?
Replies: 22
Views: 2203

Re: SPi Display Questions?

Also if we remember that it will likely be 30 years or more before the HW of the RPi 1 is pushed to its limits by the programmers that stick with it, the sooner we can start on playing with writing 100% of our VC4 code the better. People were still pushing new limits with the stock Commodore 64 in 2...
by DavidS
Fri Mar 15, 2019 4:03 pm
Forum: Graphics programming
Topic: SPi Display Questions?
Replies: 22
Views: 2203

SPi Display Questions?

Seeing more and more of these SPi displays on the market, many with between 30MHz and 50MHz max for SPI, I am wondering if it would be worth playing with these for serious projects? I see some of the 50MHz versions as large as 7 inches with advertised resolutions of up to 800x480. It seems to me tha...
by DavidS
Fri Mar 15, 2019 3:18 pm
Forum: Bare metal, Assembly language
Topic: Puzzled, Mem speed?
Replies: 31
Views: 2540

Re: Puzzled, Mem speed?

Post your code - somebody may spot something. Alright, seems a bit dull to post three instructions so was hoping not to. Here is the inner loop, and the two levels out on the loop (so as to provide something to look at): .ClrSLpC MOV R1,R0 LDR R5,FbBase MOV R2,R0 LDR R9,ScrnY MOV R3,R0 .ClrSLpY LDR...
by DavidS
Fri Mar 15, 2019 11:03 am
Forum: Bare metal, Assembly language
Topic: Puzzled, Mem speed?
Replies: 31
Views: 2540

Re: Puzzled, Mem speed?

I am doing this to figure out the maximum throughput from ARM while the VFP instruction que is kept full for other uses, thus eliminating the usabiltiy of VFP/NEON. I am aware that if it were down to simple memory copy/set operations I could speed it up a lot by using DMA channels. Though some algor...

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