How to use the disassembler#

Running the disassembler#

Moira features a built-in disassembler which allows to create textual representations for instructions, the program counter and the status register. Textual representations can be created with the following API functions:

  • int disassemble(u32 addr, char *str) const

    This functions disassembles the command at the specified address. It is the responsibility of the caller to ensure that the target string is initialized and large enough to hold the generated string. The function returns the number of bytes that the disassembled instruction occupies in memory.

  • void disassembleWord(u32 value, char *str) const

    Returns a textual representation for a single word from memory.

  • void disassembleMemory(u32 addr, int cnt, char *str) const

    Returns a textual representation for one or more words from memory.

  • void disassemblePC(u32 pc, char *str) const

    Creates a textual representation for the passed-in value of the program counter. If the first parameter is omitted, the current value of the program counter is disassembled.

  • void disassembleSR(const StatusRegister &sr, char *str) const

    Creates a textual representation for the referenced status register. If the first parameter is omitted, the current status register is disassembled.

Customizing output#

The disassembler output can be customized in various ways by calling one of the following API functions:

  • void setDasmSyntax(DasmSyntax value)

    Moira supports the following syntax styles:

    • DASM_MOIRA This is the default syntax style. It prints the instructions in Motorola syntax.

    • DASM_MOIRA_MIT This is a Moira-specific style that prints the instructions in MIT syntax.

    • DASM_GNU This style resembles the output of the m68k disassembler integrated in binutils.

    • DASM_GNU_MIT This style mimics the output of binutils when run in MIT mode.

    • DASM_MUSASHI This style reproduces the Musashi disassembler output one-by-one.

  • void setDasmNumberFormat(DasmNumberFormat value)

    The number format can be controlled by a variety of parameters which are grouped together in a singe struct:

    struct DasmNumberFormat
{
    const char *prefix;     // Prefix for hexidecimal numbers
    u8 radix;               // 10 (decimal) or 16 (hexadecimal)
    bool upperCase;         // Lettercase for hexadecimal digits A...F
    bool plainZero;         // Determines whether 0 is printed with a prefix
};

  • void setDasmLetterCase(DasmLetterCase value)

    The letter case determines the appearance of mnemonics and register names. The following options are availabe:

    • DASM_MIXED_CASE The style is determined by the selected syntax style.

    • DASM_LOWER_CASE All mnemonics and register names are printed in lowercase.

    • DASM_UPPER_CASE All mnemonics and register names are printed in uppercase.

  • void setDasmIndentation(int value)

    Defines the tabulator space between the mnemonic and the rest of the instruction.

Examples#

  • Running Moira in vAmiga with syntax style DASM_MOIRA Screenshot

  • Running Moira in vAmiga with syntax style DASM_MOIRA_MIT Screenshot