DC_Dis, Disassemble

Register parameters


IN : A = options
A7 = 1, DI_FLW : follow PC (alter next instruction pointer according jump/call and condition)
A6 = 1, DI_BYE : catch OS_Bye (exit with RC_Eof if encountered)
A5 = 1, DI_LWR : low ram protection check (exit with RC_Wrap)
BHL = extended address to be decoded (B = 0, local)
DE = buffer for null terminated disassembled intruction string
IX = registers frame (required if A7=1, see DD_Dbg for frame content)

OUT: Fc = 0, success
DE = points to byte after null terminator of mnemonic string
HL = points to next instruction
C = number of bytes decoded for instruction
A = type of instruction
A0 = 1, DO_OZCALL : RST 20h system call
A4 = 1, DO_FALSE : condition is false (jump or call cc instructions)
A5 = 1, DO_JMP : jump (absolute or relative) instruction
A6 = 1, DO_RET : ret instruction
A7 = 1, DO_CALL : call instruction

Fc = 1, failure
A = Rc_Fail, illegal instruction (returns NOP string, BHL and C updated)
A = Rc_Eof, OS_Bye encountered (if DI_BYE option enabled)
A = Rc_Wrap, next instruction is in lowram (if DI_LWR option enabled)

Registers affected after return:
    ......../IXIY same
    AFBCDEHL/.... different


  • A7, A6, A5 options are set for debugger usage, reset for a standard disassembly output
  • Low ram protection option triggers any jump or call below $2000
  • API call implemented in OZ 5.0

Related calls

DC_Dbg, Enter debugger
DC_Sbp, Set break point