"expecting an opcode mnemonic" in macro definition

[Felix Althaus]

Hello

Why does the following macro generate an error (expecting an opcode mnemonic)?

#define test(x); \
#if(0)\
#asm \
movlw 0x00 \
movlw 0x00 \
movlw 0x00 \
#endasm \
#endif \

If the if() is true (=1) everything works ok.

Thanks
Felix
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This message was ported from CCS's old forum
Original Post ID: 1170

[Tomi]

What do you mean with that #if ?
#if means: "evaluate the expression. If it is TRUE, insert the lines til #endif. If it is FALSE, IGNORE the lines til #endif".
So your code read by the compiler:
#define test(x); //Huuuuuuuhhhhhhhh?

Maybe you want to use "if" instead of "#if" ?
#define test(x) \
if(!x) \
#asm \
movlw 0x00 \
movlw 0x00 \
movlw 0x00 \
#endasm \
else \
#asm \
movlw 0xFF \
movlw 0xFF \
movlw 0xFF \
#endasm \
The list:
0000 00341 .................... test(i);
0068 08AA 00342 MOVF 2A,F
0069 1D03 00343 BTFSS 03,2
006A 286D 00344 GOTO 06D
006B 3000 00345 MOVLW 00
006C 286E 00346 GOTO 06E
006D 30FF 00347 MOVLW FF

:=Hello
:=
:=Why does the following macro generate an error (expecting an opcode mnemonic)?
:=
:=#define test(x); \
:=#if(0)\
:=#asm \
:=movlw 0x00 \
:=movlw 0x00 \
:=movlw 0x00 \
:=#endasm \
:=#endif \
:=
:=If the if() is true (=1) everything works ok.
:=
:=Thanks
:=Felix
___________________________
This message was ported from CCS's old forum
Original Post ID: 1172

[Felix Althaus]

:=What do you mean with that #if ?

I thought I can simulate (for debugging of the macro) any expression with #if(1) = TRUE (=> insert code) and #if(0) = FALSE (=> do not insert it), so I don't have to worry about the expression. But the error occurs anyway if I use a complex expression or only a 1 or 0.
___________________________
This message was ported from CCS's old forum
Original Post ID: 1174

[Tomi]

If you are in a #define directive you MUST give two parameters.
So you have two choices:
If you want to use #define all times, use #else:
#if(0) // define for NULL
#define test(x) \
#asm \
movlw 0x00 \
movlw 0x00 \
movlw 0x00 \
#endasm \
#else // define for NOT NULL
#define test(x) \
#asm \
movlw 0xFF \
movlw 0xFF \
movlw 0xFF \
#endasm \
#endif

Or you can skip the entire #define:
#if(0) \
#define test(x) \
#asm \
movlw 0x00 \
movlw 0x00 \
movlw 0x00 \
#endasm \
#endif
But in this case you don't have the test() macro (definition is skipped).

:=:=What do you mean with that #if ?
:=
:=I thought I can simulate (for debugging of the macro) any expression with #if(1) = TRUE (=> insert code) and #if(0) = FALSE (=> do not insert it), so I don't have to worry about the expression. But the error occurs anyway if I use a complex expression or only a 1 or 0.
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This message was ported from CCS's old forum
Original Post ID: 1177

[Felix Althaus]

Ok - let me begin at the beginning:

I want to write a macro, which produces a few lines of assembly code. One of these lines is a movlw instruction. The literal is calculated from the macro parameters (but there is no problem).

A few other assembly lines only will be included if the parameters meet any condition (for this I use the #if(expr) statement). My problem is now, that if the expression is true, everything works ok, but if the expression is FALSE an error (expecting opcode...) occurs.

again my code:

#define test(x); \
// any code that works ok.
#if(0)\ //only for debugging, simulates a false expression
#asm \
movlw 0x00 \ // only to simulate any code
movlw 0x00 \
movlw 0x00 \
#endasm \
#endif \

My question again: Why does this (i.e expression = FALSE) generate an error?
I thought, if this expression is false, the entire #asm section wouldn't be written.

Thanks
Felix
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This message was ported from CCS's old forum
Original Post ID: 1178

[Tomi]

Hallo Felix,
Maybe I can help you only when I can see your entire macro.
Macros are simple but they have a strong syntax.
Usually you must use a "head compiler" to read the text simply as the compiler does. It is a simple "Lego".
for example, if I write:
#define test(x) \
Restart_wdt(); \
#if(0) \
#asm \
movlw 0x00 \
movlw 0x00 \
movlw 0x00 \
#endasm \
#endif \
It gives a "missing opcode" error. The line:
#define test(x) Restart_wdt();
is terminated with a ";" what is illegal. Correct:
#define test(x) \
Restart_wdt() \
#if(0) ;\ // this is NOT an empty instruction but a terminating
#asm \
movlw 0x00 \
movlw 0x00 \
movlw 0x00 \
#endasm \
#endif \

So if the expression is continued after the common instruction(s) it is necessary to close that instr. with a ; (if it is a C instr.).
___________________________
This message was ported from CCS's old forum
Original Post ID: 1179

[Felix Althaus]

Hello

I tested the following code and it works perfectly. Thanks!
But a have still a question:

#define test(x); \
#asm \
movlw 0x00 \
#endasm \
#if(0); \
movlw 0x00 \
movlw 0x00 \
#endasm \
#asm \
movlw 0x00 \
#endif \

If I "head-compiled" it right, this code should produce:
movlw 0x00;
But why is the ; necessary in assembly?

Thanks
Felix
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This message was ported from CCS's old forum
Original Post ID: 1180

[Tomi]

Hello,
the answer is so difficult...
First of all, there is a confusion about using #asm #endasm pairs. Legally you must use them as BEGIN - END pairs.
About the Q: 0 is never TRUE so the line is theoretically "movlw 0x00" (; is missing). Let's talk about the soul of the compilers: they know a compiler directive as a NEW LINE starts with "#". But on the other hand the #define directive must fit only one line. The "\" is not a trick: it is for a better readibility but your macro is an exact one-line expression after the pre-processing. So what about a #if in a #define directive? In the expression:
#define mymacro #if(0) ........ #endif
the #if(0) is not at the beginning of the line. Fortunately you are lucky and CCS C not always senses the difference between the <CR-LF> line-terminator and the ";" command delimiter (as my favorite professor said: "This is not a bug. This is a new feature."). Shortly: in your example the ";" is a "directive delimiter" ("hardly line break") not defined in standard C.

Once more, it would be better to use the standard C and write this:
#if(0)
#define test(x); \
#asm \
movlw 0x00 \
#endasm
#else
#define test(x); \
#asm \
movlw 0x00 \
movlw 0x00 \
movlw 0x00 \
movlw 0x00 \
#endasm
#endif

Pay attention on the "\" chars: use them only if it is necessary (not in all lines).


___________________________
This message was ported from CCS's old forum
Original Post ID: 1181

[Felix Althaus]

Thanks

You use
#if(0)
#define test(x);

But I have a problem with it: In the if expression I use the macro parameters and so it doesn' seem to work.

mfg

Felix
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This message was ported from CCS's old forum
Original Post ID: 1182

[Tomi]

Hajaj,
Maybe now I understand what you mean. But the input parameter is either a RAM variable or a pre-defined constant (like _DEBUG)?
Be careful with #if: it is evaluated on compile time, so you could not enter a variable or reference for it. You must use a constant expression, e.g.:
#define VERSION 0x0300
#define MAINVERSION 0x03
#define SUBVERSION 0x01
#if (VERSION >= 0x0300)
#if (VERSION >= (MAINVERSION << 8) | SUBVERSION)
etc.

If your input parameter "x" is a variable it is exists only at run-time but not in compile time.

:=Thanks
:=
:=You use
:=#if(0)
:=#define test(x);
:=
:=But I have a problem with it: In the if expression I use the macro parameters and so it doesn' seem to work.
:=
:=mfg
:=
:=Felix
___________________________
This message was ported from CCS's old forum
Original Post ID: 1183

[Felix Althaus]

:=Maybe now I understand what you mean. But the input parameter is either a RAM variable or a pre-defined constant (like _DEBUG)?

The parameters are predefined constants (from a *.h file).
___________________________
This message was ported from CCS's old forum
Original Post ID: 1184