Motorola M68CPU32BUG Manuel d'utilisateur télécharger pdf (Page 57)

SYSTEM CALLS

M68CPU32BUG/D REV 1 5-2

It is necessary to create an equate file with the routine names equated to their respective codes, or

download the archive file C32SCALL.ARC from the Motorola FREEWARE Bulletin Board

(BBS). For more information on the FREEWARE BBS, reference customer letter

M68xxxEVx/L2.

When using the CPU32Bug one-line assembler/disassembler, the SYSCALL macro and the

equates are pre-defined. Input: SYSCALL, space, function, carriage return.

EXAMPLE

CPU32Bug>M 3000;DI<CR>

0000 3000 00000000 ORI.B #$0,D0? SYSCALL .OUTLN <CR>

0000 3000 4E3F0022 SYSCALL .OUTLN

0000 3004 00000000 ORI.B #$0,D0? . <CR>

CPU32Bug>

5.1.2 Input/Output String Formats

Within the context of the TRAP #15 handler are three string formats:

Pointer/Pointer Format The string is defined by a pointer to the first character and a

pointer to the last character + 1.

Pointer/Count Format The string is defined by a pointer to a count byte which

contains the count of the characters in the string followed by

the string itself.

Line Format A line is defined as a string followed by a carriage return and a

line feed.

5.2 SYSTEM CALL ROUTINES

Table 5-1 summarizes the TRAP #15 functions. Refer to the appropriate paragraph for a

description of the available system calls.

ASSEMBLER/DISASSEMBLER

M68CPU32BUG/D 4-11

4.3.1 Executing the Assembler/Disassembler

The assembler/disassembler is actuated using the ;DI option of the MM (Memory Modify) and

MD (Memory Display) commands:

MM <ADDR >;DI

where

<CR> sequences to next instruction

.<CR> exits command

and

MD[S] <ADDR>[:<count>I<ADDR>];DI

Use the MM (;DI option) to enter and modify the program. When this command is used, the

memory contents at the specified location are disassembled and displayed. A new or modified

line can be entered if desired.

The disassembled line is either an M68300 Family instruction, a SYSCALL, or a DC.W

directive. If the disassembler recognizes a valid form of an instruction, the instruction is returned.

If the disassembler does not recognizes a valid form of an instruction, random data occurs, the

DC.W $XXXX (always hex) is returned. Because the disassembler gives precedence to

instructions, a word of data interpreted as a valid instruction is returned as the instruction.

4.3.2 Entering a Source Line

Enter a new source line immediately following the disassembled line. Use the format discussed

in paragraph 4.2.1.

CPU32Bug>MM 6000;DI <CR>

00006000 2600 MOVE.L D0,D3 ? ADDQ.L #1,A3 <CR>

When a line is terminated with a carriage return, the old source line is erased from the terminal

screen, the new line is assembled and displayed, and the next instruction in memory is

disassembled and displayed:

CPU32Bug>MM 6000;DI<CR>

00006000 528B ADDQ.L #1,A3

00006002 4282 CLR.L D2 ?

Another program line can now be entered. Program entry continues in like manner until all lines

have been entered. A period (.) is used to exit the MM command. If an error occurs during line

assembly, the assembler displays the line unassembled with an error message. The location being

accessed is redisplayed:

CPU32Bug>MM 6000;di <CR>

00006000 528B ADDQ.L #$1,A3? LEA.L 5(A0,D8),A4<CR>

LEA.L 5(A0,D8),A4

BAD COMBINATION OF COMMAND, OPERANDS

00006000 528B ADDQ.L #$1,A3?

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Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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Motorola M68CPU32BUG Manuel d'utilisateur Page 57

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