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Re: [avr-gcc-list] Time-efficient read of high byte in two-byte variable

From: Wallace White
Subject: Re: [avr-gcc-list] Time-efficient read of high byte in two-byte variable
Date: Thu, 08 May 2003 16:30:44 -0700
User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.3.1) Gecko/20030425

E. Weddington wrote:
Let's see, my variable in question is a signed int... so I could
change the typedef union

typedef union
 int16_t word;
 hilow_t byte;
} mytype ;

and tack on .word to all my references to that variable... that should
be fine, right?


Hmm. Well it's up to you as to how you want to handle the signed issue. Do you want the high byte to be signed? or unsigned? Do you want the low byte to be signed as well?

I don't really care which byte carries the sign... I'd just like to be able to use the variable as a regular signed int in the rest of the program--where it is used in math functions--while efficiently accessing its high byte during the function that spits the variable out the UART.

The efficiency isn't critical for this application, really, so I may just keep doing it the way I had been. But thanks, Eric and Ralph, for the suggestions.

- Wallace

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