td_asm.txt

tasm source document descript

language is Assembler,

  [ES:DI],20m

specifies that you want to look at a raw hex memory dump of the 20 bytes
pointed to by the ES:DI register pair.


Source-level debugging
======================
You can step through your assembler code using a Module window just as
with any of the high-level languages. If you want to see the register
values, you can put a Registers window to the right of the Module window.

Sometimes, you may want to use a CPU window and see your source code as
well. To do this, open a CPU window and choose the Code pane's Mixed
command until it reads Both. That way you can see both your source code
and machine code bytes. Remember to zoom the CPU window (by pressing F5)
if you want to see the machine code bytes.


Examining and changing registers
================================
The obvious way to change registers is to highlight a register in either
a CPU window or Registers window. A quick way to change a register is to
choose Data|Evaluate/Modify. You can enter an assignment expression that
directly modifies a register's contents. For example,

   SI = 99

loads the SI register with 99.

Likewise, you can examine registers using the same technique. For example,

   Alt-D E AX

shows you the value of the AX register.


=========================================
5. Inline assembler keywords
=========================================
This section lists the instruction mnemonics and other special symbols that
you use when entering instructions with the inline assembler. The keywords
presented here are the same as those used by Turbo Assembler.


8086/80186/80286 instructional mnemonics
_________________________________________
  AAA        INC        LIDT**     REPNZ
  AAD        INSB*      LLDT**     REPZ
  AAM        INSW*      LMSW**     RET
  AAS        INT        LOCK       REFT
  ADC        INTO       LODSB      ROL
  ADD        IRET       LODSW      ROR
  AND        JB         LOOP       SAHF
  ARPL**     JBE        LOOPNZ     SAR
  BOUND*     JCXZ       LOOPZ      SBB
  CALL       JE         LSL**      SCASB
  CLC        JL         LTR**      SCASW
  CLD        JLE        MOV        SGDT**
  CLI        JMP        MOVSB      SHL
  CLTS**     JNB        MOVSW      SHR
  CMC        JNBE       MUL        SLDT**
  CMP        JNE        NEG        SMSW**
  CMPSB      JNLE       NOP        STC
  CMPSW      JNO        NOT        STD
  CWD        JNP        OR         STI
  DAA        JO         OUT        STOSB
  DAS        JP         OUTSB      STOSW
  DEC        JS         OUTSW      STR**
  DIV        LAHF       POP        SUB
  ENTER*     LAR**      POPA*      TEST
  ESC        LDS        POPF       WAIT
  HLT        LEA        PUSH       VERR**
  IDIV       LEAVE      PUSHA*     VERW**
  IMUL       LES        PUSHF      XCHG
  IN         LGDT**     RCL        XLAT
                                   XOR
___________________________________________

* Available only when running on the 186 and 286 processor
** Available only when running on the 286 processor


Turbo Debugger supports all 80386 and 80387 instruction
mnemonics and registers:

80386 instruction mnemonics
_________________________________________

  BSF        LSS         SETG        SETS
  BSR        MOVSX       SETL        SHLD
  BT         MOVZX       SETLE       SHRD
  BTC        POPAD       SETNB       CMPSD
  BTR        POPFD       SETNE       STOSD
  BTS        PUSHAD      SETNL       LODSD
  CDQ        PUSHFD      SETNO       MOVSD
  CWDE       SETA        SETNP       SCASD
  IRETD      SETB        SETNS       INSD
  LFS        SETBE       SETO        OUTSD
  LGS        SETE        SETP        JECXZ
__________________________________________

80486 instruction mnemonics
_________________________________________

       BSWAP               INVLPG
       CMPXCHG             WBINVD
       INVD                XADD
_________________________________________

80386 registers
_________________________________________

       EAX                 EDI
       EBX                 EBP
       ECX                 ESP
       EDX                 FS
       ESI                 GS
_________________________________________

CPU registers
__________________________________________________________________

Byte registers            AH, AL, BH, BL, CH, CL, DH, DL

Word registers            AX, BX, CX, DX, SI, DI, SP, BP, FLAGS

Segment registers         CS, DS, ES, SS

Floating registers        ST, ST(0), ST(1), ST(2), ST(3), ST(4),
                          ST(5), ST(6), ST(7)
___________________________________________________________________

Special keywords
_________________________________________

       WORD PTR            TBYTE PTR
       BYTE PTR            NEAR
       DWORD PTR           FAR
       QWORD PTR           SHORT
_________________________________________

8087/80287 numeric coprocessor instruction mnemonics
____________________________________________________
  FABS       FIADD      FLDL2E     FST
  FADD       FIACOM     FLDL2T     FSTCW
  FADDP      FIACOMP    FLDPI      FSTENV
  FBLD       FIDIV      FLDZ       FSTP
  FBSTP      FIDIVR     FLD1       FSTSW**
  FCHS       FILD       FMUL       FSUB
  FCLEX      FIMUL      FMULP      FSUBP
  FCOM       FINCSTP    FNOP       FSUBR
  FCOMP      FINIT      FNSTS**    FSUBRP
  FCOMPP     FIST       FPATAN     FTST
  FDECSTP    FISTP      FPREM      FWAIT
  FDISI      FISUB      FPTAN      FXAM
  FDIV       FISUBR     FRNDINT    FXCH
  FDIVP      FLD        FSAVENT    FXTRACT
  FDIVR      FLDCWR     FSCALE     FYL2X
  FDIVRP     FLDENV     FSETPM*    FYL2XPI
  FENI       FLDLG2     FSQRT      F2XM1
  FFREE      FLDLN2     
_____________________________________________________

* Available only when running on the 287 numeric coprocessor.
** On the 80287, the fstsw instruction can use the AX register as an
   operand, as well as the normal memory operand.


80387 instruction mnemonics
_________________________________________

       FCOS                FUCOM
       FSIN                FUCOMP
       FPREM1              FUCOMPP
       FSINCOS
_________________________________________


The 80x87 coprocessor chip and emulator
=======================================
This section is for programmers who are familiar with the operation
if the 80x87 math coprocessor. If your program uses floating-point
numbers, Turbo Debugger lets you examine and change the state of the numeric
coprocessor or, if the coprocessor is emulated, examine the state of the
software emulator. (Windows permits you only to examine the state of the
emulator, not to change it.)  You don't need to use the capabilities
described in this chapter to debug programs that use floating-point numbers,
although some very subtle bugs may be easier to find.

In this section, we discuss the differences between the 80x87 chip and
the software emulator. We also describe the Numeric Processor window and
show you how to examine and modify the floating-point registers, the status
bits, and the control bits.


The 80x87 chip vs. the emulator
===============================
TDW automatically detects whether your program is using the math chip or the
emulator and adjusts its behavior accordingly.

Note that most programs use either the emulator or the math chip, not both
within the same program. If you have written special assembler code that
uses both, TDW won't be able to show you the status of the math chip; it
reports on the emulator only.


=========================================
6. The Numeric Processor window
=========================================
You create a Numeric Processor window by choosing the View|Numeric Processor
command from the menu bar. The line at the top of the window shows the
current instruction pointer, opcode, and data pointer. The instruction
pointer is both shown as a 20-bit physical address. The data pointer is
either a 16-bit or a 20-bit address, depending on the memory model. You
can convert 20-bit addresses to segment and offset form by using the first
four digits as the segment value and the last digit as the offset value.

For example, if the top line shows IPTR=5A669, you can treat this as the
address 5a66:9 if you want to examine the current data and instruction in
a CPU window. This window has three panes: The left pane (Register pane)
shows the contents of the floating-point registers, the middle pane
(Control pane) shows the control flags, and the right pane (Status pane)
shows the status flags.

The top line shows you the following information about the last floating-
point operation that was executed:

o Emulator indicates that the numeric processor is being emulated. If there
  were a numeric processor, 8087, 80287, 80387, or 80486 would appear instead.

o The IPTR shows the 20-bit physical address from which the last floating-
  point instruction was fetched.

o The OPCODE shows the instruction type that was fetched.

o The OPTR shows the 16-bit or 20-bit physical address of the memory address
  that the instruction referenced, if any.


The Register pane
-----------------

    The 80-bit floating-point registers
    -----------------------------------

    The Register pane shows each of the floating-point registers, ST(0) to
    ST(7), along with its status (valid/zero/special/empty). The contents
    are shown as an 80-bit floating-point number.

    If you've zoomed the Numeric Processor window (by pressing F5) or made
    it wider by using Window|Size/Move, you'll also see the floating-point
    registers displayed as raw hex bytes.


    The Register pane's local menu
    ------------------------------
    ___________
   | Zero      |
   | Empty     |
   | Change... |
   |___________|

    To bring up the Register pane local menu, press Alt-F10, or use the Ctrl
    key with the first letter of the desired command to directly access the
    command.

    Zero
    ----
    Sets the value of the currently highlighted register to zero.

    Empty
    -----
    Sets the value of the currently highlighted register to empty. This is a
    special status that indicates that the register no longer contains valid
    data.

    Change
    ------
    Loads a new value into the currently highlighted register. You are
    prompted for the value to load. You can enter an integer or floating-
    point value, using the current language's expression parser. The value
    you enter is automatically converted to the 80-bit temporary real format
    used by the numeric coprocessor.

    You can also invoke this command by simply starting to type the new value
    for the floating-point register. A dialog box appears, exactly as if you
    had specified the Change command.


The Control pane
----------------

    The control bits
    ----------------

    The following table lists the different control flags and how they
    appear in the Control pane:
_________________________________________

   Name in pane         Flag description__

      im                Invalid operation mask
      dm                Denormalized operand mask
      zm                Zero divide mask
      om                Overflow mask
      um                Underflow mask
      pm                Precision mask
      iem               Interrupt enable mask (8087 only)
      pc                Precision control
      rc                Rounding control
      ic                Infinity control__


    The Control pane's local menu
    -----------------------------
       ________
      | Toggle |
      |________|

    Press Tab to go to the Control pane, then press Alt-F10 to pop up the
    local menu. (Alternatively, you can use the Ctrl key with the first letter
    of the desired command to access it.)

    Toggle
    ------
    Cycles through the values that the currently highlighted control flag
    can be set to. Most flags can only be set or cleared (0 or 1), so this
    command just toggles the flag to the other value. Some other flags have
    more than two values; for those flags, this command increments the flag
    value until the maximum value is reached, and then sets it back to zero.

    You can also toggle the control flag values by highlighting them and
    pressing Enter.


The Status pane
---------------

    The status bits
    ---------------

    The following table lists the different status flags and how they appear
    in the Status pane:
____________________________________

   Name in pane         Flag description__

      ie                Invalid operation
      de                Denormalized operand
      ze                Zero divide
      oe                Overflow
      ue                Underflow
      pe                Precision
      ir                Interrupt request
      cc                Condition code
      st                Stack top pointer_


    The Status pane's local menu
    ----------------------------
       ________
      | Toggle |
      |________|

    Press Tab to move to the Statuspane, then press Alt-F10 to pop up the
    local menu. (You can also use the Ctrl key with the first letter of the
    desired command to access the command directly.)


    Toggle
    ------
    Cycles through the values that the currently highlighted status flag
    can be set to. Most flags can only be set or cleared (0 or 1), so this
    command just toggles the flag to the other value. Some other flags have
    more than two values; for those flags, this command increments the
    flag value until the maximum value is reached, and then sets it back to
    zero.

    You can also toggle the status flag values by highlighting them and
    pressing Enter.

/***************************** END OF FILE *******************************/