M (modify)

Syntax

  MA   offset   [count] [base] [newvalue(s)]     ABS relative
  MD   dst.off  [count] [base] [newvalue(s)]     Data segment
  MDB  offset   [count] [base] [newvalue(s)]     DB relative
  MS   offset   [count] [base] [newvalue(s)]     S relative
  MQ   offset   [count] [base] [newvalue(s)]     Q relative

  MC   logaddr  [count] [base] [newvalue(s)]     Program file (default)
  MCG  logaddr  [count] [base] [newvalue(s)]     Group library
  MCP  logaddr  [count] [base] [newvalue(s)]     Account library
  MCLG logaddr  [count] [base] [newvalue(s)]     Logon group
  MCLP logaddr  [count] [base] [newvalue(s)]     Logon account
  MCS  logaddr  [count] [base] [newvalue(s)]     System library
  MCU  fname logaddr  [count] [base] [newvalue(s)]  User library
  MCA  cmabsaddr  [count] [base] [newvalue(s)]   Absolute CST
  MCAX cmabsaddr  [count] [base] [newvalue(s)]   Absolute CSTX

  MV   virtaddr   [count] [base] [newvalue(s)]   Virtual
  MZ   realaddr   [count] [base] [newvalue(s)]   Real memory

  MSEC ldev.off   [count] [base] [newvalue(s)]   Secondary store

Parameters

offset

MA, MDB, MQ, MS only. The CM word offset that specifies the relative starting location of the area to be modified.

logaddr

MC, MCG, MCP, MCLG, MCLP, MS, MCU only. A full logical code address (LCPTR) specifies three necessary items:

• The logical code file (PROG, GRP, SYS, and so on.).

• NM: the virtual space ID number (SID).

  CM: the logical segment number.

• NM: the virtual byte offset within the space.

  CM: the word offset within the code segment.

Logical code addresses can be specified in various levels of detail:

• As a full logical code pointer (LCPTR):

  MC procname+20

  Procedure name lookups return LCPTRs.

  MC pw+4

  Predefined ENV variables of type LCPTR.

  MC SYS(2.200)

  Explicit coercion to a LCPTR type.

• As a long pointer (LPTR):

  MC 23.2644

  sid.offset or seg.offset

  The logical file is determined based upon the command suffix. For example:

  • MC implies PROG

  • MCG implies GRP

  • MCS implies SYS, and so on

• As a short pointer (SPTR):

  MC 1024

  offset only

  For NM, the short pointer offset is converted to a long pointer using the function STOLOG, which looks up the SID of the loaded logical file. This is different from the standard short to long pointer conversion, STOL, which is based on the current space registers (SRs).

  For CM, the current executing logical segment number and the current executing logical file are used to build a LCPTR.

The search path used for procedure name lookups is based on the command suffix letter:

MC

Full search path:

• NM: PROG, GRP, PUB, USER(s), SYS

• CM: PROG, GRP, PUB, LGRP, LPUB, SYS

MCG

Search GRP, the group library.

MCP

Search PUB, the account library.

MCLG

Search LGRP, the logon group library.

MCLP

Search LPUB, the logon account library.

MCS

Search SYS, the system library.

MCU

Search USER, the user library.

For a full description of logical code addresses, refer to the section "Logical Code Addresses" in Chapter 2.

fname

MCU only. The file name of the NM user library. Since multiple NM libraries can be bound with the XL= option on a RUN command,

   :run nmprog; xl=lib1,lib2.testgrp,lib3

it is necessary to specify the desired NM user library. For example:

   MCU lib1 204c
   MCU lib2.testgrp test20+1c0

If the file name is not fully qualified, the following defaults are used:

• Default account: the account of the program file.

• Default group: the group of the program file.

cmabsaddr

MCA, MCAX only. A full CM absolute code address specifies three necessary items:

• Either the CST or the CSTX.

• The absolute code segment number.

• The CM word offset within the code segment.

Absolute code addresses can be specified in two ways:

• As a long pointer (LPTR):

  MCA 23.2644

  Implicit CST 23.2644

  MCAX 5.3204

  Implicit CSTX 5.3204

• As a full absolute code pointer (ACPTR):

  MCA CST(2.200)

  Explicit CST coercion

  MCAX CSTX(2.200)

  Explicit CSTX coercion

  MCAX logtoabs(prog(1.20))

  Explicit absolute conversion

The search path used for procedure name lookups is based on the command suffix letter:

MCA

GRP, PUB, LGRP, LPUB, SYS

MCAX

PROG

virtaddr

MV only. The virtual address to be modified.

Virtaddr can be a short pointer, a long pointer, or a full logical code pointer.

realaddr

MZ only. The real mode memory address to be modified.

ldev.off

MSEC only. The logical device number (LDEV) and byte offset of the data on disk to be displayed. This address is entered in the form ldev.byteoffset.

count

MA, MC, MD, MDB, MS, MQ: The number of CM 16-bit words to be modified.

MC, MV, MZ: The number of NM 32-bit words to be modified.

If omitted, a single line of values is modified.

base

The desired representation mode for output values:

% or OCTAL

Octal representation

# or DECIMAL

Decimal representation

$ or HEXADECIMAL

Hexadecimal representation

ASCII

ASCII representation

This parameter can be abbreviated to as little as a single character.

If omitted, the current output base is used.

newvalue(s)

The new values for the specified locations. Specified new values are automatically assigned to the locations until the new values are exhausted. If the new values are omitted, or if they run out, Debug prompts for the remaining new values. To retain the original value, simply press Return. The character dot "." can be entered to abort the modification loop. All locations modified before the dot is encountered are permanently changed.

Examples

---

   $nmdebug > mv sp-2c,,,4
   $ Virt 21.40050780 = '....'  $e7       := 4

Modify value at SP-2c, replacing it with $4.

   %cmdebug > md 1.64,6,h
   $ DST 1.34   = "v4"  $7634 := %111
   $ DST 1.35   = ".."  $5    :=       (retain original value)
   $ DST 1.36   = ".."  $fffa := $c0
   $ DST 1.37   = ".."  $fff0 := 1234
   $ DST 1.38   = ".."  $0    := .
   current/remaining modifications aborted at user request

Modify 6 words starting at DST 1.64. Display values (and addresses) in hex.

• DST 1.34 is assigned a new value of %111.

• DST 1.35 retains its original value of %5.

• DST 1.36 is assigned a new value of $c0.

• DST 1.37 is assigned a new value of 1234.

• Dot "." terminates modifications.

The modifications for DST 1.34 through 1.37 have been successfully completed.

   %cmdebug > mq-30,6
   % Q-30     = ".P"  %27120  := "AB"
   % Q-27     = "UB"  %52502  := 'CD'
   % Q-26     = ".S"  %27123  := u16("EF")
   % Q-25     = "YS"  %54523  :=
   % Q-24     = ".."  %177772 := [q-2]
   % Q-23     = ".."  %7      := !s + (1000-[db+22]/2)

Modify 6 words starting at Q-%30. The current values are displayed in ASCII and octal (current output base).

• Q-30 is assigned the (implicitly coerced) integer value of "AB".

• Q-27 is assigned the implicitly coerced) integer value of 'CD'.

• Q-26 is assigned the explicitly coerced unsigned 16-bit integer value of "EF".

• Q-25 is left unchanged.

• Q-24 is assigned the contents of Q-2.

• Q-23 is assigned the value of the S register + (1000 - the contents of DB+22 divided by 2).

Limitations, Restrictions

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When CM code has been translated, modification of the original object code has no effect. The NM translated code must be modified.

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