Inline Assembly - Accessing Each Byte Of An Int? Options

[kenh]

Hello,

I would like to ask if it is possible to reference the individual bytes of an int from an inline assembly asm {} block, and if so, what is the syntax?

One example where this would be useful is to optimize the capture of Timer1 values to an unsigned int variable

e.g.

unsigned int x;
x = (tmr1h<<8)+tmr1l;

I would like to be able to write something like

asm
{
movf _tmr1h, W
movwf _x.h
movf _tmr1l, W
movwf _x.l
}

I have tried various approaches with struct/unions and pointers, but without success.

This post has been edited by kenh: Feb 7 2007, 10:39 PM

[cac001]

You are not trying hard enough for a C only solution.

CODE

typedef union {
unsigned int ui;
unsigned char b[2];
} noportable_int;

//main program starts here.    
void main()

{
noportable_int n;

n.ui = 0x1234;
00AF  3034      MOVLW 0x34
00B0  1283      BCF STATUS, RP0
00B1  1303      BCF STATUS, RP1
00B2  00AD      MOVWF main_1_n
00B3  3012      MOVLW 0x12
00B4  00AE      MOVWF main_1_n+D'1'

n.b[0] = tmr1l;
00B5  080E      MOVF gbl_tmr1l, W
00B6  00AD      MOVWF main_1_n

n.b[1] = tmr1h;
00B7  080F      MOVF gbl_tmr1h, W
00B8  00AE      MOVWF main_1_n+D'1'

}