Motorola Axiom CMD11E1 Guía de usuario descargar pdf (Pagina 37)

3.5. YOUR SECOND FUNCTION 37

code for 0 or the code for 1 depending on whether the carry is cleared or set

Note the function involves a counting loop.

We now have to decide register usage: We will use the A register to pass the

value to the function. Internally, this value will be moved to B as A is needed in

all the calls to BUFFALO routines. We need a counter, and we will use the X

all registers we will use.

Here is the complete code for the function.

;;;;;;;;;;;;;;;;;;;;;Start: PRBINARY;;;;;;;;;;;;;;;;;;;;

; Function: PRBINARY

; Purpose: To print a value in binary

;

; Inputs: Value to be printed is passed in the A register

;

; Returns: None

;

; Registers affected: None. The values in the registers are stored

; first and these values are restored at the end.

;

; Notes: The output consists of two parts. The value in A is first

; printed in HEX, and then in binary

;

PRBINARY

; first save the registers we will be using: a, b and x

PSHA

PSHB

PSHX

; copy a to be for later use

TAB

; print a as hex number (2 digits).

; print the left digit

JSR OUTLHLF

Conveniently, the code for 1 is one more than the code for 0. So we load A with the code

for 0 and add the carry to it

1 2 ... 32 33 34 35 36 37 38 39 40 41 42 ... 100 101

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Motorola Axiom CMD11E1 Guía de usuario Pagina 37