RE: [avr-gcc-list] Using in/out Instructions with ATmega128
-Original Message- From: avr-gcc-list-bounces+eric.weddington=atmel@nongnu.org [mailto:avr-gcc-list-bounces+eric.weddington=atmel@nongnu. org] On Behalf Of Thomas D. Dean Sent: Monday, May 04, 2009 4:37 PM To: avr-gcc-list@nongnu.org Subject: [avr-gcc-list] Using in/out Instructions with ATmega128 I have # avr-gcc --version avr-gcc (GCC) 4.3.2 Copyright (C) 2008 Free Software Foundation, Inc. ... I want to use the ATmega128 and in/out instructions for registers below 0x40. # avr-gcc -mmcu=atmega128 -c -o 4x40-lcd.o xxx.c # avr-gcc-mmcu=atmega128 4x40-lcd.o -o xxx.elf -lc # avr-objdump -d xxx.elf ... 804: a2 e3 ldi r26, 0x32 ; 50 806: b0 e0 ldi r27, 0x00 ; 0 808: e2 e3 ldi r30, 0x32 ; 50 80a: f0 e0 ldi r31, 0x00 ; 0 80c: 80 81 ld r24, Z 80e: 8f 70 andir24, 0x0F ; 15 810: 80 62 ori r24, 0x20 ; 32 812: 8c 93 st X, r24 ... This can be done with four instructions, in, andi, ori, and, out. And, 6 fewer clocks. Where is the source code that corresponds to the above assembly? ___ AVR-GCC-list mailing list AVR-GCC-list@nongnu.org http://lists.nongnu.org/mailman/listinfo/avr-gcc-list
RE: [avr-gcc-list] Using in/out Instructions with ATmega128
-Original Message- From: avr-gcc-list-bounces+eric.weddington=atmel@nongnu.org [mailto:avr-gcc-list-bounces+eric.weddington=atmel@nongnu. org] On Behalf Of Thomas D. Dean Sent: Monday, May 04, 2009 4:37 PM To: avr-gcc-list@nongnu.org Subject: [avr-gcc-list] Using in/out Instructions with ATmega128 I have # avr-gcc --version avr-gcc (GCC) 4.3.2 Copyright (C) 2008 Free Software Foundation, Inc. ... I want to use the ATmega128 and in/out instructions for registers below 0x40. # avr-gcc -mmcu=atmega128 -c -o 4x40-lcd.o xxx.c Also, you need to turn optimization on to get those IN/OUT instructions. Add -Os to your compiler flags. ___ AVR-GCC-list mailing list AVR-GCC-list@nongnu.org http://lists.nongnu.org/mailman/listinfo/avr-gcc-list
RE: [avr-gcc-list] Using in/out Instructions with ATmega128
-Original Message- From: Thomas D. Dean [mailto:tomd...@speakeasy.org] Sent: Monday, May 04, 2009 5:24 PM To: Weddington, Eric Subject: RE: [avr-gcc-list] Using in/out Instructions with ATmega128 On Mon, 2009-05-04 at 17:08 -0600, Weddington, Eric wrote: Also, you need to turn optimization on to get those IN/OUT instructions. Add -Os to your compiler flags. Thanks, -o3 gets covered by -o fname later in the command stream! No. The switches are case sensitive, just like the C language itself. You want to use an uppercase 'O', not lowercase. It is better if you optimize for size, rather than for speed. This is why it is suggested to use -Os, not -O3. And please also reply to the list and not just to me personally. ___ AVR-GCC-list mailing list AVR-GCC-list@nongnu.org http://lists.nongnu.org/mailman/listinfo/avr-gcc-list
