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My attempt to multi-thread an audio talk-though program using batches of data. M. Smith Electrical and Computer Engineering University of Calgary, Smithmr @ ucalgary.ca. Laboratory 5 – Done in “C and C++”. Stage 1 – 30%

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my attempt to multi thread an audio talk though program using batches of data

My attempt to multi-thread an audio talk-though program using batches of data

M. Smith

Electrical and Computer Engineering

University of Calgary,

Smithmr @ ucalgary.ca

laboratory 5 done in c and c
Laboratory 5 – Done in “C and C++”
  • Stage 1 – 30%
    • Develop and investigate a multi-tasking system where the threads are free-running. Thread tasks are “Sleep(time_task)”
    • Develop and investigate a multi-tasking system where the threads communicate through semaphores to control order of operation
  • Stage 2 – 55%
    • Demonstrate and investigate turning an “audio – talk-through program” into a multi-threaded system – one point processed per interrupt
  • Stage 3 – 15%
    • Demonstrate a batch processing system as a multi-threaded system
  • Options
    • Use SHARC ADSP-21061 boards (40 MHz) – existing audio-libraries – have not attempted
    • Use Blackfin ADSP-BF533 boards (600 MHz) – existing audio-libraries – have been successful at home, but not here
    • Use Blackfin ADSP-BF533 boards (600 MHz) – using very simple, no frills, audio-talk though library – surprising simple with 1 to 32 points being processed. Fails with 33 points. Code logic issue, not a timing issue as I can waste 25000 cycles per block at 32 points
laboratory 5 done in c and c1
Laboratory 5 – Done in “C and C++”
  • Stage 1 – 30%
    • Develop and investigate a multi-tasking system where the threads are free-running. Thread tasks are “Sleep(time_task)”
    • Develop and investigate a multi-tasking system where the threads communicate through semaphores to control order of operation
  • Stage 2 – 55%
    • Demonstrate and investigate turning an “audio – talk-through program” into a multi-threaded system – one point processed per interrupt
  • Stage 3 – 15%
    • Demonstrate a batch processing system as a multi-threaded system
  • Options
    • Use SHARC ADSP-21061 boards (40 MHz) – existing audio-libraries – have not attempted
    • Use Blackfin ADSP-BF533 boards (600 MHz) – existing audio-libraries – have been successful at home, but not here
    • Use Blackfin ADSP-BF533 boards (600 MHz) – using very simple, no frills, audio-talk though library – surprising simple with 1 to 32 points being processed. Fails with 33 points. Code logic issue, not a timing issue as I can waste 25000 cycles per block at 32 points
nett result
Nett Result

Not working as expected – equal priority (5) on each task

We are obviously missing samples

changing priorities
Changing Priorities

Priorities

ReadThread 3 -- obviously the most critical

ProcessThread 5

WriteThread 5

different priorities
Different Priorities

Priorities

ReadThread 3 -- obviously the most critical

ProcessThread 5

WriteThread 4

no idle time available optimize the code
No idle time available – Optimize the code

Priorities

ReadThread 3

ProcessThread 5

WriteThread 5

Priorities

ReadThread 3

ProcessThread 5

WriteThread 4

net result
Net Result

TOTAL SYSTEM HANG

BLOCKED SEMAPHORES

tried a number of things
Tried a number of things

Worked out which semaphore was blocking

Different priorities

Different TIC times

Better – but obviously missing cycles – particularly write

final test result
Final Test Result

Seems to behaving as expected

However – when changed MAXIMUM COUNT FOR READ / WRITE ISR Semaphores – status history changes

This could indicate that missing some interrupts

Could mean nothing – interrupts asynchronous to timer TICs

could handle 800 waste times every 32 samples plenty of time 50000 cycles
Could handle 800 waste “times” every 32 samples – plenty of time 50000 cycles +

Inner loop =2 * BUFFERLENGTHOuter loop = Wastetime * (3 + INNER)

Total = 13 + Inner loop

BUFFER = 32, waste time = 800

Cycles around 800 * 64 = 50000+

68K Blackfin SHARC

D0 (8) R0 (16) R0

A0 (6) P0 (with a bit of MIPS) (6)

I0 (4) I0 (16)

real life test small buffers
Real life test -- small buffers
  • Absolutely nothing
  • However
    • 4 audio connections in
    • 6 audio connections out
  • Got the correct connections
    • Set buffer = 1 – worked first time
    • Set buffer = 32 – worked first time
larger buffers
Larger buffers
  • BUFFERSIZE – 64 – out of bsz memory error
  • Fix .LDF file – manually (GUI window works how?)

MEMORY

{

mem_VDK_strt { TYPE(RAM) START(0xFFA00000) END(0xFFA00003) WIDTH(8) }

mem_l1_code { TYPE(RAM) START(0xFFA00004) END(0xFFA0FFFF) WIDTH(8) }

mem_l1_code_cache { TYPE(RAM) START(0xFFA10000) END(0xFFA13FFF) WIDTH(8) }

mem_EVT_all { TYPE(RAM) START(0xFF900000) END(0xFF900003) WIDTH(8) }

mem_EVT_NMI { TYPE(RAM) START(0xFF900004) END(0xFF900007) WIDTH(8) }

mem_EVT_EVX { TYPE(RAM) START(0xFF900008) END(0xFF90000B) WIDTH(8) }

mem_EVT_IRPTEN { TYPE(RAM) START(0xFF90000C) END(0xFF90000F) WIDTH(8) }

mem_EVT_IVHW { TYPE(RAM) START(0xFF900010) END(0xFF900013) WIDTH(8) }

mem_EVT_IVTMR { TYPE(RAM) START(0xFF900014) END(0xFF900017) WIDTH(8) }

mem_EVT_IVG7 { TYPE(RAM) START(0xFF900018) END(0xFF90001B) WIDTH(8) }

mem_EVT_IVG8 { TYPE(RAM) START(0xFF90001C) END(0xFF90001F) WIDTH(8) }

mem_EVT_IVG9 { TYPE(RAM) START(0xFF900020) END(0xFF900023) WIDTH(8) }

mem_EVT_IVG10 { TYPE(RAM) START(0xFF900024) END(0xFF900027) WIDTH(8) }

mem_EVT_IVG11 { TYPE(RAM) START(0xFF900028) END(0xFF90002B) WIDTH(8) }

mem_EVT_IVG12 { TYPE(RAM) START(0xFF90002C) END(0xFF90002F) WIDTH(8) }

mem_EVT_IVG13 { TYPE(RAM) START(0xFF900030) END(0xFF900033) WIDTH(8) }

mem_EVT_IVG14 { TYPE(RAM) START(0xFF900034) END(0xFF900037) WIDTH(8) }

mem_EVT_IVG15 { TYPE(RAM) START(0xFF900038) END(0xFF90003B) WIDTH(8) }

mem_sysstack { TYPE(RAM) START(0xFF90003C) END(0xFF90083B) WIDTH(8) }

mem_l1_data_b { TYPE(RAM) START(0xFF90083C) END(0xFF903FFF) WIDTH(8) }

mem_l1_data_b_cache { TYPE(RAM) START(0xFF904000) END(0xFF907FFF) WIDTH(8) }

memory issues on 64 point data batches
Memory issues – on 64 point data batches
  • Still did not work
    • Did I change the memory map correctly?
    • No – seems okay as works with 32 – but perhaps having caching issue
  • Went back to old memory map
    • Went to configure external SDRAM and use that
    • Modified only 1 array – left channel
      • Left channel fails – right channel works
  • Spending too much time in context switching
    • Group ReadThread and WriteThread code together
    • Does not even work with 32 !!!!!!
  • Am convinced that there is a logical issue associated with the semaphore handling.
bonus 20 bonus
Bonus – 20% bonus
  • If you can get all parts of Lab. 5 running and then solve this issue of why fails at 64 points (even when not wasting cycles) – 20% bonus on this lab. marks and either a mention or a “co-author-ship” on one of the Circuit Cellar articles
  • May even be worth some money if I manage to sell the articles
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