Unexpected integer cast warning on register

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mdemde
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#1
Posted by mdemde: Thu. Mar 12, 2015 - 05:00 PM
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So, I've got a pointer in an timer CTC interrupt ISR(TIMER0_COMPA_vect)   

static const unsigned char *timing_pointer = brightness_timings;

pointing to a constant array of chars

const unsigned char brightness_timings[MAX_BRIGHTNESS+1] = {blah blah blah}

and I'm setting OCR0A (compare register for timer 0, an 8-bit register) during its interrupt:

	OCR0A = timing_pointer++;

When I compile with avr-gcc (4.8.2) I get this warning for that instruction:

assignment makes integer from pointer without a cast

I don't see any integers anywhere... can anyone tell me why this is happening?

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Tools, Compilers and General Programming
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Gold Markclawson
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This reply has been marked as the solution. 
Posted by clawson: Thu. Mar 12, 2015 - 05:02 PM
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OCR0A = timing_pointer++;

surely you mean

OCR0A = *timing_pointer++;

You want something out of the array - not the address of the data - so you need a pointer dereference.

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KIIV_cz
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Posted by KIIV_cz: Thu. Mar 12, 2015 - 05:14 PM (Reply to #2)
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Hope he didn't mean smiley:

  OCR0A = (*timing_pointer)++;

Edit: But unlikely with const pointer

Computers don't make errors - What they do they do on purpose.

Last Edited: Thu. Mar 12, 2015 - 05:17 PM
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mdemde
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Posted by mdemde: Thu. Mar 12, 2015 - 05:19 PM (Reply to #2)
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clawson wrote:

surely you mean

OCR0A = *timing_pointer++;

You want something out of the array - not the address of the data - so you need a pointer dereference.

Ah... that'll be it. Thanks!

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