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From: | Kang Tin LAI |
Subject: | Re: [avr-gcc-list] swap bits |
Date: | Thu, 23 Jan 2003 00:19:40 +0800 |
User-agent: | Mozilla/5.0 (X11; U; Linux i586; en-US; rv:0.9.4.1) Gecko/20020508 Netscape6/6.2.3 |
May reduce the hardware port pin by using 4-bit nibble connection: PA0 - PA7 PA1 - PA6 PA2 - PA5 PA3 - PA4 with few additional instructions to combine nibbles back to byte. -- --- Kang Tin LAI <address@hidden> ----- Klaus Rudolph wrote:
Volkmar Dierkes wrote: I have another, but not really a good idea...perhaps :-)What do you mean with efficiently? bytes or time?or IO-Pins? Make port A output and port B input. Make a wirering port A[0]->portB[7] ....You need only two bytes flash for program + initialisation and waste no registers :-)init: ldi r16, 0xff out ddra, r16 reverse_r16: out porta, r16 in r16, portb 4 words flash, and 4 cycles access time. Thats really effectiv! Bye Klaus avr-gcc-list at http://avr1.org
avr-gcc-list at http://avr1.org
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