New Saturn asm "add loop" benchmark for the HP48G

[Jonathan Busby]

(10-27-2023 07:26 AM)Werner Wrote:  

(10-26-2023 05:24 PM)Jonathan Busby Wrote:  

Code:

        P=      0
        C=0     W
l1      C=C+1   WP
        GONC    l1
        P=P+1
        C=C+1   P
        GONC    l1

Wouldn't using the A-field be faster?

Code:

  P=5
  C=0 W
- C=C+1 A
  GONC -
  C=C+1 P
  GONC -
  P=P+1
  GONC -

D'oh! Very clever Once again I am blinded by my monomania, this time directed towards the custom interrupt routine -- I hadn't given the inner add loop a second thought in terms of performance. In a perfect world, the "C=C+1 WP" instruction would only take two cycles to decode -- and that's what I overlooked. Already at P = 4 , the cycle time of "C=C+1 WP" equals the 7 cycles ( ignoring memory access considerations ) of the "C=C+1 A" instruction. If you really want to go nuts, you could unroll the increment code for the B field in a variation on J-F Garnier's code

Your original A field code brings the count up to around 4382026. So, a few hundred thousand more, but I was hoping for something more dramatic considering the code for an unoptimized HP-71B assembly language add loop, which runs ats 640KHz, reaches over 1E6 in 60 seconds.

Anyways, it seems my ISR code is bugged ( the IRAM reconfiguration code is flawless ) in some strange way which I still trying to work out ( it doesn't help that I have chronic sleep deprivation ( really ) and I got up at around 4 AM today ). So, I left out checking for C.A overflow when TIMER2 generates an interrupt. This means it's *possible* that an interrupt could corrupt the count, but it's unlikely, and you'd know it if it happened -- I plan on having this fixed soon.

Quote:Cheers, Werner

Regards,

Jonathan