Motorola USB08 Instrucciones de operaciones descargar pdf (Pagina 63)

The readability of disassembly listings may be enhanced by checking 'UnAsm: add spaces at code

breaks' on the Settings>Debug tab. This will add a blank line in unassembly listings after the following

instructions:

• Unconditional jumps, including the BRA (Branch Always) instruction. No space is left if the

jump address is that of the immediately following instruction, i.e. the jump was included simply

to use up processor cycles.

• Return from Interrupt, RTI

• Return from Subroutine, RTS

8.28 Using a Symbol Table

A symbol file may be nominated to Xplor8 so that when addresses are encountered during disassembly

which match a symbol value, then the symbol is displayed instead of the address. The symbol file is a

plain text file. Xplor8 will cope with any file, provided that:

1. The symbol name appears first on the line;

2. The symbol value appears next, and is separated from the name by at least one space, comma

or tab character. The value must be in hexadecimal but it is optional for it to be preceded by a '$' sign

3. After the value any characters will be ignored, for example: comments, occurrences of the

symbol, etc. (provided they are separated from the value by at least one space, comma or tab

character)

4. Lines which cannot be interpreted as being a name followed by a value are ignored. This means

that most heading lines will be discounted.

5. Some assemblers introduce the ASCII form feed character, $0C, at the top of the listing - all

control characters are ignored.

To make use a symbol file, select one of the radio buttons on the Settings>Debug tab. If the nominated

file cannot be found, or cannot be interpreted, no symbol table will be loaded. The example given in

the description of the Unassemble command (page 62) might look like this if a symbol table was in use:

0001: F800 RomStart C6FFC0 LDA $FFC0

0002: F803 A1FF CMP #$FF

0003: F805 2703 BEQ No_Trim

0004: F807 C7FC00 STA $FC00

0005: F80A No_Trim 6E091F MOV #$09,CONFIG1

0006: F80D 6E081E MOV #$08,CONFIG2

0007: F810 450C80 LDHX #$0C80

0008: F813 Delay 5BFE DBNZX Delay

0009: F815 6E0236 MOV #$02,OSCSTAT

0010: F818 3F80 CLR RamStart

1 2 ... 58 59 60 61 62 63 64 65 66 67 68 ... 99 100

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Motorola USB08 Instrucciones de operaciones Pagina 63