Re: avr-gcc ABI: return 8-bit value from function

Benoit,

See "C WITHOUT RAM" section of this 2006 article named "Tiny AVR Serial 
Port Programmer".

http://www.lightner.net/avr/2605018Lightner.pdf

...and this Webpage...

http://www.lightner.net/avr/ATtinyAvrGcc.html

Compiling C-code for an AVR like the ATtiny2313 with few resources---and 
zero SRAM---is indeed practical.

But today STMicro sells tiny 32-bit STM32 ARM microcontroller chips 
(e.g., STM32L021D4P7, 5mm x 6mm TSSOP-14) with plenty of program flash 
and SRAM for under $1 US.  STM even claims "32-bits for 32-cents" in 
large volumes for their ARM Cortex chips.

https://www.electronicspecifier.com/micros/stm32f030-stm32-stmicroelectronics-value-line-microcontrollers-32-bits-for-32-cents

Best regards,

Bruce

------------------------------------------------------------------------
On 6/4/2018 7:35 PM, Erik Christiansen wrote:
> Reply-To: [email protected]
>
> On 04.06.18 19:19, Benoit Steinmetz wrote:
>> p.s:  I have recently started a topic on avrfreaks about this issue [2].
> Your link has caused me to visit avrfreaks for the second time in a
> decade, leading me to wonder if answers would appear here. Normally I'd
> point to the useful software admonition "Be conservative in what you
> output, and liberal in tolerance of input.", but I see that your target
> is an ATtiny2313. With only 1K instructions available, I'm surprised
> to see any 'C' used at all, and understand the desire to trim every
> superfluous instruction.
>
> One question: Does the omission of sign extension by avr-gcc remain
> without optimisation for size?
>
> My current project, also on an ATtiny2313, is 100% assembler -
> simplified event scheduler, state machines, HAL, the lot. But at least
> you could fall back to an ATtiny4313 if the 'C' blows out, I guess.
>
> Erik
>
>
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-- 
*Bruce D. Lightner*
*Lightner Engineering*
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