Assembly Macro Help

DWT

Greetings,

It was my understanding that there was an instruction, mov32, that would allow you to move a 32-bit value into a register. However, when I try to use this instruction I get a compiler error. It seems that the compiler does not recognize the instruction. I therefore decided to write a macro that would move a 32-bit value into a register. The code that I have written is shown below, but I am having some trouble compiling. I would appreciate any help with this code snippet.

movw		.macro	rx, n1, n2
			mov		rx, #n1, lsl #16
			orr		rx, rx, #n2
			.endm

Kind Regards,

Willis

over 13 years ago

0 Haixiao Weng over 13 years ago

TI__Genius 13810 points

There is no 32bit immediate mov instruction.

I will get back to you on the rest of your question as soon as possible.

Regards,

Haixiao

0 Haixiao Weng over 13 years ago in reply to Haixiao Weng

TI__Genius 13810 points

Try:

mov_32 .macro rx, ry, rz

movw rx, ry;

lsl rx, rx, #16

add rx, rx, rz

.endm

When you call it, for example:

mov_32 r1, #0xFFFF, #100

Regards,

Haixiao

0 DWT over 13 years ago in reply to Haixiao Weng

Intellectual 260 points

Okay what is the movw instruction doing? Also, when you call the macro should there not be two 16 bit values? Why is the second value #100?

Regards, Willis

EDIT: Is movw just the macro that I wrote? or is it an arm instruction.

0 Haixiao Weng over 13 years ago in reply to Haixiao Weng

TI__Genius 13810 points

movw is the 16bit immediate number arm move instruction.

The 3rd instruction add rx, rx, rz should be replaced by 2 instruction because add instruction only support 8bit immediate number move.

mov_32 .macro rx, ry, rz

movw rx, ry;

lsl rx, rx, #16

movw r11, rz

add rx, rx, r11

.endm

Please note that I used r11 here.

0 Haixiao Weng over 13 years ago in reply to Haixiao Weng

TI__Genius 13810 points

This one:

mov_32 .macro rx, ry, rz

movw rx, ry;

movw r11, rz;

add rx, rx, r11,lsl #16

.endm

You can call

mov_32 r1, #0xFFFF, #0xF00F

0 DWT over 13 years ago in reply to Haixiao Weng

Intellectual 260 points

When I compile I get an error related to movw. The compiler tell me that this is only available in v7. I am compiling using the command line.

"SCI1.asm", ERROR! at line 65: [E0002) Instruction only available in V7

movw rx, ry

What exactly does this error mean?

Thanks

0 KGreb over 13 years ago in reply to DWT

TI__Mastermind 23000 points

v7 = ARM version 7 architecture, which was the first version of ARM architecture to support the MOVW instruction. Have you specified the compile target? Believe the necessary command line syntax is "-mv7R4" for Cortex R4.

Regards,

Karl

0 KGreb over 13 years ago in reply to Haixiao Weng

TI__Mastermind 23000 points

Note that some of the other ARM compilers, such as ARM's RVCT, are not terribly clear in explaining what is a macro vs. what is a hardware instruction in the CPU. For example, there is an "addressing mode" in RVCT for 32b immediate load which actually is a macro that resolves to multiple instructions, as you have suggested.

Regards,

Karl

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