#HIGH assembly operator problem

Posted on November 17, 2005 at 12:15

liotro78,

from your reply I see that my explanation was not clear...

If the assembler does not accept LD A,#HIGH(Buffer_0), the workaround is to find in the C code the high byte of Buffer_0 address and store it somewhere (e.g. in Buffer_0H).

The C macro HIGH is OK because it is similar to this one:

#define HIBYTE(w) ((BYTE) (((WORD) (w) >> 8) & 0xFF))

which is the one used by the Microsoft Visual C++.

The compilation errors seems therefore strange.

Perhaps they are due to the mix of languages; anyway if Buffer_0H is a valid label, there is no reason for the assembler to complain.

If you look at the Woro listing, you can see that HIGH(Buffer_0) is 0x01 (A6 is the opcode for the loading of a constant in the accumulator).

You can therefore replace LD A,HIGH(Buffer_0) with LD A,#1 which works as long as &Buffer_0[0] is located in page 1.

EtaPhi

BTW: your vectors are quite large. Are you sure that Buffer_0[1024] will fit in RAM? Few ST7 microcontrollers have so much memory...

Posted on November 17, 2005 at 15:30

Etaphy i have used this code:

#define HIGH(x) ((x) >> 8)

const unsigned char Buffer_0H = HIGH(Buffer_0); <---ERRORS!!

asm

{

LD A, #Buffer_0

LD pScan:1, A

LD A, Buffer_0H

LD pScan, A

}

and appears 2 errors in constant declaration...

ERROR C1826: Integer-expression expected

ERROR C2207: Initializer must be constant

I have sent a message at metrowerks support for resolving finaly the HIGH problem, because it's impossible that this operator is undefined, because i have the last version of CST7 and AST7 that allow this operator.

[ This message was edited by: liotro78 on 18-11-2005 12:36 ]

Posted on November 21, 2005 at 16:22

Probblem resolved:

in the new codewarrior for ST7 the HIGH operator have changed from :

HIGH(VAR)

to:

%HIGH(VAR)

then the correctly code is:

asm

{

LD A, #Buffer_0

LD pScan:1, A

LD A, #%HIGH(Buffer_0)

LD pScan, A

}