mirror of
https://github.com/mcgurk/Arduino-USB-HID-RetroJoystickAdapter
synced 2024-12-21 23:18:56 -05:00
| .. | ||
| 4joy_adapter_old.ino | ||
| 4joy_adapter.ino | ||
| interrupt_test.ino | ||
| README.md | ||
| stuff.ino | ||
| temp.ino | ||
& 'C:\Program Files (x86)\Arduino\hardware\tools\avr\bin\avr-objdump.exe' -S "C:\\Users\\lehti\\AppData\\Local\\Temp\\arduino_build_208947/c64_4joystick-adapter.ino.elf" > c:\temp\koe.txt
cli // 1 clock
PORTB = *ptr; // is this atomic? probably, because ptr is 6-bit pointer. nope...
f98: e0 91 26 01 lds r30, 0x0126 ; 0x800126 <__data_end> // 2 clocks
f9c: f0 91 27 01 lds r31, 0x0127 ; 0x800127 <__data_end+0x1> // 2 clocks
fa0: 80 81 ld r24, Z // 1 clock
fa2: 85 b9 out 0x05, r24 ; 5 // 1 clock
sei // 1 clock
500ns
cli
mov r31, r1
mov r30, gpior0
ld r24, Z
out 0x05, r24
sei
375ns
using data/i/o space
- lds can load from io (if +0x20 added to address) or data space
- sts can store from register to io (if +0x20 added to address) or data space
- in can load from io to register
- out can write from register to io
- only one io/data address space access within one instruction?
- lds/sts takes 2 cycles and in/out takes 1 cycle? ldi takes 1 cycle?
- lds/sts: "M" _SFR_MEM_ADDR(GPIOR2), in/out: "I" _SFR_IO_ADDR(GPIOR0)
avr asm
- http://www.nongnu.org/avr-libc/user-manual/inline_asm.html
- https://ucexperiment.wordpress.com/2016/03/04/arduino-inline-assembly-tutorial-1/
- https://ucexperiment.wordpress.com/2016/03/11/arduino-inline-assembly-tutorial-5-2/
atomic
- https://groups.google.com/a/arduino.cc/g/developers/c/cmu0Qy32zxY
- http://www.gammon.com.au/forum/?id=11488
- https://home.csulb.edu/~hill/ee346/Lectures/10%20ATmega32U4%20Interrupts.pdf
register as variable
- https://forum.arduino.cc/index.php?topic=43760.5
- http://www.nongnu.org/avr-libc/user-manual/FAQ.html#faq_regbind
- volatile register unsigned char my_register asm("r2");
- https://www.avrfreaks.net/forum/binding-variable-register
running code from ram
- https://forum.arduino.cc/index.php?topic=425962.0
- https://forum.arduino.cc/index.php?topic=470631.0
- "AVRs are Harvard architecture CPUs, so they CANNOT run code out of RAM, so that directive can't possibly do anything of any value whatsoever."
- "Yes, Harvard IS the reason. A Harvard CPU, by definition, has separate code and data memory spaces. They execute code from one memory, and fetch data from a different memory. What you're seeing is most likely the compiler pretending the directive can do what you want, but the linker doing the only thing it can do - putting that code in FLASH."