The latest version of Earle Philhower’s Arduino core for the RP2350 now allows you to access the RISC-V core on the RP2350. So you have the option of running uLisp in RISC-V code rather than ARM code.
Performance
How does the RISC-V core perform? Here are the same benchmarks as I use on the Performance page:
| Processor | Architecture | Clock | Objects | Image | Code | GC time | Tak | Q2 | FFT |
|---|---|---|---|---|---|---|---|---|---|
| RP2350 | ARM | 150 MHz | 47000 | All | Yes | 5.0 ms | 3.3 s | 8.9 s | 95 ms |
| RP2350 | RISC-V | 150 MHz | 42500 | All | Yes | 4.3 ms | 2.9 s | 7.6 s | 97 ms |
Installing uLisp on the RP2350
Whichever architecture you want to use, upload the ARM version of uLisp. See the updated instructions here for how to install it: Raspberry Pi Pico 2.
Why go RISC-V?
Why would you want to run uLisp on the RISC-V core?
One reason is to learn RISC-V assembler, and experiment with writing machine-code RISC-V programs, using the built-in machine code feature in uLisp together with the RISC-V assembler written in Lisp.
For example, here’s a simple RISC-V machine code program to calculate the Greatest Common Divisor of two numbers:
; Greatest Common Divisor
(defcode gcd (a b)
swap
($mv 'a2 'a1)
($mv 'a1 'a0)
again
($mv 'a0 'a2)
($sub 'a2 'a2 'a1)
($bltz 'a2 swap)
($bnez 'a2 again)
($ret))
To find the GCD of 3287 and 3460:
> (gcd 3287 3460)
173
For more information see: RISC-V assembler overview.
For example programs see: RISC-V assembler examples.
Update: Corrected the clock frequency in the table.