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Author Topic: Integer maths > 16 bits  (Read 506 times)

MarkMLl

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Integer maths > 16 bits
« on: September 15, 2024, 04:08:09 pm »
What are the options for 32-, 64- and 128-bit five-function integer maths on devices like the RP2040 and arbitrary RISC-V targets, with minimal external dependencies?

Area of application is hash algorithms etc., with the assumption (please) that hardware support for these will not be available.

MarkMLl
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Thaddy

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Re: Integer maths > 16 bits
« Reply #1 on: September 15, 2024, 07:29:52 pm »
All you need is rolls, shifts, and, or, xor, not and a byte array.
This stems from the olden days. Easiest if there are not signs involved.
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MarkMLl

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Re: Integer maths > 16 bits
« Reply #2 on: September 15, 2024, 07:52:54 pm »
Actually Thaddy, I need + -  * div mod and shr. I'm /entirely/ capable of writing them in assembler... I'd just rather not.

MarkMLl
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PascalDragon

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Re: Integer maths > 16 bits
« Reply #3 on: September 15, 2024, 09:01:22 pm »
Quote from: MarkMLl on September 15, 2024, 04:08:09 pm
What are the options for 32-, 64- and 128-bit five-function integer maths on devices like the RP2040 and arbitrary RISC-V targets, with minimal external dependencies?

At least 32- and 64-bit math should be fully supported at least if you compile the RTL using software floating point (assuming the processor in question does not support the operations in hardware). If hardware support is available then everything should work out fine if you simply compile for the target.

Only for 128-bit math I don't know right now whether we have some suitable unit already.
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MarkMLl

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Re: Integer maths > 16 bits
« Reply #4 on: September 15, 2024, 09:47:37 pm »
Quote from: PascalDragon on September 15, 2024, 09:01:22 pm
Only for 128-bit math I don't know right now whether we have some suitable unit already.

ATM it's the 128-bit case that's most interesting, but I thought I'd build up gradually through the other types since they might not (by default at least) be implemented on small chips.

MarkMLl
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MathMan

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Re: Integer maths > 16 bits
« Reply #5 on: September 16, 2024, 08:02:56 am »
Hi MarkMLI,

Take a look at the attached. Though not fully fleshed - missing some stuff for signed integers - it may be a good starting point. External dependency - FPC has to provide support up to 64 bit types, which I understand from PascalDragons response can be assumed.

If you want/need to extend, then pls let me know. Maybe I can help.

Cheers,
MathMan
« Last Edit: September 16, 2024, 08:08:27 am by MathMan »
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440bx

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Re: Integer maths > 16 bits
« Reply #6 on: September 16, 2024, 08:06:24 am »
MathMan, you got a typo in your signature/name.
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MathMan

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Re: Integer maths > 16 bits
« Reply #7 on: September 16, 2024, 08:09:42 am »
Quote from: 440bx on September 16, 2024, 08:06:24 am
MathMan, you got a typo in your signature/name.

Thanks for the heads up - getting lazy with the internal spell checker routines  :D
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MarkMLl

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Re: Integer maths > 16 bits
« Reply #8 on: September 16, 2024, 08:49:10 am »
Quote from: MathMan on September 16, 2024, 08:02:56 am
Hi MarkMLI,

Take a look at the attached. Though not fully fleshed - missing some stuff for signed integers - it may be a good starting point. External dependency - FPC has to provide support up to 64 bit types, which I understand from PascalDragons response can be assumed.

If you want/need to extend, then pls let me know. Maybe I can help.

Cheers,
MathMan

Many thanks I'll look at that- not necessarily immediately, but definitely.

MarkMLl
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Logitech, TopSpeed & FTL Modula-2 on bare metal (Z80, '286 protected mode).
Pet hate: people who boast about the size and sophistication of their computer.
GitHub repositories: https://github.com/MarkMLl?tab=repositories
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