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OpenVMS Linker Utility Manual
A.4.1 Stack Commands
The stack commands place bytes, words, and longwords on the stack. Byte
and word stack commands (except those that stack the values of global
symbols or addresses) have signed-extension-to-longword format and
zero-extension-to-longword format.
The data placed on the stack is taken from one of the following sources:
- The DATA field directly following the COMMAND field
- A global symbol
- A computation derived from the base address of a program section
Table A-3 lists the stack commands and related codes, together with
a brief description of each command.
Table A-3 Stack Commands
| Code |
Command |
Description |
|
0
|
TIR$C_STA_GBL (Stack Global)
|
Data is the name of the global symbol in standard name format. The
command stacks the 32-bit binary value of the stacks symbol.
|
|
1
|
TIR$C_STA_SB (Stack Signed Byte)
|
Data is a 1-byte constant, which is sign-extended to 32 bits.
|
|
2
|
TIR$C_STA_SW (Stack Signed Word)
|
Data is a 2-byte constant, which is sign-extended to 32 bits.
|
|
3
|
TIR$C_STA_LW (Stack Longword)
|
Data is a 4-byte constant.
|
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4
|
TIR$C_STA_PB (Stack Psect Base Plus Byte Offset)
|
Data is a 1-byte program section index followed by a single signed byte
offset
1. The psect base and byte offset are added and stacked.
|
|
5
|
TIR$C_STA_PW (Stack Psect Base Plus Word Offset)
|
Data is a 1-byte program section index followed by a single signed word
offset
1. The psect base and word offset are added and stacked.
|
|
6
|
TIR$C_STA_PL (Stack Psect Base Plus Longword Offset)
|
Data is a 1-byte program section index followed by a single signed
longword offset
1. The psect base and longword offset are added and stacked.
|
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7
|
TIR$C_STA_UB (Stack Unsigned Byte)
|
Same as Stack Signed Byte except that the value is zero-extended to 32
bits.
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8
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TIR$C_STA_UW (Stack Unsigned Word)
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Same as Stack Signed Word except that the value is zero-extended to 32
bits.
|
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9
|
TIR$C_STA_BFI (Stack Byte From Image)
|
This command is reserved for use by Compaq. The top longword on the
stack is used as an address, in the image, from which to retrieve a
byte. The byte is zero-extended and replaces the top longword on the
stack.
|
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10
|
TIR$C_STA_WFI (Stack Word From Image)
|
This command is reserved for use by Compaq. It is the word equivalent
of the previous command.
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11
|
TIR$C_STA_LFI (Stack Longword From Image)
|
This command is reserved for use by Compaq. It is the longword
equivalent of the previous two commands.
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12
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TIR$C_STA_EPM (Stack Entry Point Mask)
|
This command has the same format as the Stack Global command. However,
it stacks the entry point mask (unsigned stack's word) that accompanies
the symbol definition, rather than the symbol value. An error results
if the symbol is not an entry point.
|
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13
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TIR$C_STA_CKARG (Compare Procedure Argument and Stack for TRUE or FALSE)
|
This command checks to see whether the argument passing mechanism
(ARG$V_PASSMECH) in the formal argument descriptor matches the argument
passing mechanism in the actual argument descriptor. The DATA field for
this command consists of the ASCIC symbol name in standard name format
(1 count byte followed by the symbol name (1 to 31 bytes)). This is
followed by the 1-byte argument index and the actual argument
descriptor. The format of the actual argument descriptor is the same as
the format of the formal argument descriptor described in
Section A.3.4. The linker compares the values of ARG$V_PASSMECH for the
formal and actual argument descriptors. If these values agree or if
there is no formal argument descriptor, the linker places the TRUE
value on top of the stack; otherwise, it stacks the FALSE value.
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14
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TIR$C_STA_WPB (Stack Psect Base Plus Byte Offset with Word Psect)
|
Same as TIR$C_STA_PB except the program section index is a word rather
than a byte.
|
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15
|
TIR$C_STA_WPW (Stack Psect Base Plus Word Offset with Word Psect)
|
Same as TIR$C_STA_PW except the program section index is a word rather
than a byte.
|
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16
|
TIR$C_STA_WPL (Stack Psect Base Plus Longword Offset with Word Psect)
|
Same as TIR$C_STA_PL except the program section index is a word rather
than a byte.
|
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17
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TIR$C_STA_LSY (Stack Local Symbol Value)
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Data is a 2-byte environment index followed by the ASCIC symbol name in
standard name format.
|
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18
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TIR$C_STA_LIT (Stack Literal)
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Data is a 1-byte index of the literal to be stacked. If the literal has
not been defined, the linker stacks zero and issues an error message.
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19
|
TIR$C_STA_LEPM (Stack Local Symbol Entry Point Mask)
|
This command has the same format as the Stack Local Symbol Value
command and the same action as the Stack Entry Point Mask command.
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1Although this command provides for a signed offset value,
negative offsets are rarely correct. Note too that the base address is
that of this module's contribution to the program section.
A.4.2 Store Commands
The store commands pop the top longword from the stack and write it to
the output image file. Several store commands provide validation of the
quantity being stored, with the possibility of issuing truncation
errors during the operation. After a store command is executed, the
location counter is pointing to the next byte in the output image.
Table A-4 lists the store commands and related codes, together with
a brief description of each command.
Table A-4 Store Commands
| Code |
Command |
Description |
|
20
|
TIR$C_STO_SB (Store Signed Byte)
|
Low byte is written to image. Bits 31:7 must be identical.
|
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21
|
TIR$C_STO_SW (Store Signed Word)
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Low word is written to image. Bits 31:15 must be identical.
|
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22
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TIR$C_STO_LW (Store Longword)
|
One longword is written to image.
|
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23
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TIR$C_STO_BD (Store Byte Displaced)
|
Current location counter plus 1 is subtracted from the top longword on
the stack. Low byte of resulting value is written to image. Bits 31:7
must be identical.
|
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24
|
TIR$C_STO_WD (Store Word Displaced)
|
Current location counter plus 2 is subtracted from the top longword on
the stack. Low word of resulting value is written to image. Bits 31:15
must be identical.
|
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25
|
TIR$C_STO_LD (Store Longword Displaced)
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Current location counter plus 4 is subtracted from the top longword on
the stack. Resulting value is written to image.
|
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26
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TIR$C_STO_LI (Store Short Literal)
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Low byte of top longword on the stack is written to image. Bits 31:6
must be zero.
|
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27
|
TIR$C_STO_PIDR (Store Position-Independent Data Reference)
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The longword on top of the stack is the address of a data item. If the
address is absolute, the longword is written to the image. If the
address is relocatable, the linker stores information in the image file
to allow the image activator to initialize the location when the image
is run.
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28
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TIR$C_STO_PICR (Store Position-Independent Code Reference)
|
The purpose of this command is to generate a position-independent code
reference. The top longword on stack is the address of an item to which
a position-independent instruction makes reference. If the item is
absolute, the byte 9F hexadecimal (the operand specifier for absolute
addressing mode) followed by the top longword on the stack are written
to the image, and the location counter is incremented. If the item is
relocatable, the byte EF hexadecimal (the operand specifier for
longword relative addressing mode) is written to the image; the top
longword on the stack is Store Longword Displaced (see TIR$C_STO_LD);
and the location counter is incremented. If the item is relocatable and
contained in a shareable image, the byte FF (the operand specifier for
longword relative deferred addressing mode) is written to the image;
the top longword on the stack is Store Longword Displaced (target is in
the EXIT vector); and the location counter is incremented.
|
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29
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TIR$C_STO_RSB (Store Repeated Signed Byte)
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The longword on top of the stack is used as a repeat count. The low
byte of the next longword on the stack is then written to the image the
indicated number of times. Both longwords are removed from the stack
upon completion. See note in Section A.4 regarding the use of this
command with zeros.
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30
|
TIR$C_STO_RSW (Store Repeated Signed Word)
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Same as previous command except that a word rather than a byte is
written.
|
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31
|
TIR$C_STO_RL (Store Repeated Longword)
|
Same as previous two commands except that a longword is written.
|
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32
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TIR$C_STO_VPS (Store Arbitrary Field)
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This command writes a bit field to the image. The data field consists
of an unsigned byte containing the value p, followed by another
unsigned byte containing the value s. Bits 0 to s--1 of the top
longword on the stack are written to the image starting at bit p of the
current location. Only the specified bits of the image are altered.
After the operation, the location counter is the address of the byte
containing bit (p+s) of the location modified. Note that the value of
p+s must be greater than zero and less than or equal to either 32 or
((P+8)/8)8--1, whichever is less. In other words, the bit field must be
contained within a single byte.
|
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33
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TIR$C_STO_USB (Store Unsigned Byte)
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Same as TIR$C_STO_SB except that bits 31:8 must be zero.
|
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34
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TIR$C_STO_USW (Store Unsigned Word)
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Same as TIR$C_STO_SW except that bits 31:16 must be zero.
|
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35
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TIR$C_STO_RUB (Store Repeated Unsigned Byte)
|
Same as TIR$C_STO_RSB except that bits 31:8 of the stored byte must be
zero.
|
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36
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TIR$C_STO_RUW (Store Repeated Unsigned Word)
|
Same as TIR$C_STO_RSW except that bits 31:16 of the stored word must be
zero.
|
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37
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TIR$C_STO_B (Store Byte)
|
This command writes the low byte of the top longword on the stack to
the image file. It thus permits any 8-bit value (the top longword must
contain a value from --128 to 255) to be written to the image. If the
top longword on the stack is negative, then bits 31:7 must be 1; if
positive, then bits 31:8 must be zero.
|
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38
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TIR$C_STO_W (Store Word)
|
This command writes the low word of the top longword on the stack to
the image file. It thus permits any 16-bit value (the top longword must
contain a value from --32768 to 65535) to be written to the image. If
the top longword on the stack is negative, bits 31:15 must be 1; if
positive, the bits 31:16 must be zero.
|
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39
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TIR$C_STO_RB (Store Repeated Byte)
|
The top longword on the stack is used as a repeat count. The low byte
of the next longword on the stack is then written to the image the
indicated number of times. This is the repeated version of Store Byte
(see TIR$C_STO_B).
|
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40
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TIR$C_STO_RW (Store Repeated Word)
|
This is the word version of the Store Repeated Byte command.
|
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41
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TIR$C_STO_RIVB (Store Repeated Immediate Variable Bytes)
|
Data is a 1-byte count
n field followed by
n bytes of data. These
n bytes of data are written to the image the number of times
specified by the top longword on the stack (which is removed from the
stack upon completion of the command). If the top longword on the stack
is zero, nothing is stored.
|
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42
|
TIR$C_STO_PIRR (Store Position-Independent Reference Relative)
|
The longword (longword 1) on the top of the stack is the address of a
data item. If the data item is absolute, the command is the same as the
Store Longword command except that the next longword on the stack
(following the top one) is also removed from the stack upon completion
of the command. If the data item is relocatable, the value of the
second longword (longword 2) on the stack is checked. If its value is
--1, the current value of the location counter is substituted for
longword 2, and the value stored is longword 1 minus longword 2. Both
longwords are removed from the stack upon completion of the command.
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43--49
|
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Reserved.
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A.4.3 Operator Commands
Operator commands perform arithmetic operations on the top one or two
longwords on the stack. Upon completion of the operation, the result is
the top longword on the stack.
The linker evaluates expressions in Post Fix Polish form. All
arithmetic operations are performed in signed 32-bit two's complement
integers. There is no provision for floating-point, string, or quadword
computation. Attempts to divide by zero produce a zero result and a
nonfatal warning message.
Table A-5 lists the operator commands and related codes, together
with a brief description of each command.
Table A-5 Operator Commands
| Code |
Command |
Description |
|
50
|
TIR$C_OPR_NOP (No-Operation)
|
No operation results.
|
|
51
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TIR$C_OPR_ADD (Add)
|
Top two longwords on the stack are added.
|
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52
|
TIR$C_OPR_SUB (Subtract)
|
Top longword on the stack is subtracted from the next longword on the
stack.
|
|
53
|
TIR$C_OPR_MUL (Multiply)
|
Top two longwords on the stack are multiplied.
|
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54
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TIR$C_OPR_DIV (Divide)
|
Top longword on the stack is divided into the next longword on the
stack.
|
|
55
|
TIR$C_OPR_AND (Logical AND)
|
Logical AND of top two longwords.
|
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56
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TIR$C_OPR_IOR (Logical Inclusive OR)
|
Inclusive OR of top two longwords.
|
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57
|
TIR$C_OPR_EOR (Logical Exclusive OR)
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Exclusive OR of top two longwords.
|
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58
|
TIR$C_OPR_NEG (Negate)
|
Top longword is negated.
|
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59
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TIR$C_OPR_COM (Complement)
|
Top longword is complemented.
|
|
60
|
TIR$C_OPR_INSV (Insert Field)
|
This command is reserved. It is similar to TIR$C_STO_VPS except that
the bit field is written to the next longword on the stack instead of
to the image file. The location counter is therefore unaffected. After
completion of the command, only the top longword on the stack is
removed.
|
|
61
|
TIR$C_OPR_ASH (Arithmetic Shift)
|
The top longword on the stack specifies the shift count and direction
to be applied to the next longword on the stack. When the top longword
is negative, bits in the next longword are shifted right with
replication of the sign bit. When the top longword is positive, bits in
the next longword are shifted left with zeros moved into low-order bits.
|
|
62
|
TIR$C_OPR_USH (Unsigned Shift)
|
Same as previous command except that, for a shift right, zeros are
always moved into the high bits.
|
|
63
|
TIR$C_OPR_ROT (Rotate)
|
The top longword on the stack specifies the rotate count and direction
to be applied to the next longword on the stack. When the top longword
is positive, the next longword is rotated left; when negative, right.
The top longword must have an absolute value of 0 to 32.
|
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64
|
TIR$C_OPR_SEL (Select)
|
This command manipulates the top three longwords on the stack. If the
top longword has the value TRUE (low bit set), it and the next (second)
longword on the stack are removed, leaving the third longword
(unchanged) on top of the stack. If the top longword has the value
FALSE (low bit clear), the value of the next (second) longword is
copied to the following (third) longword, and the top and second
longwords are removed, leaving the third (now having the value of the
second) on top of the stack. Thus, the command collapses three
longwords on the stack to a single longword that has the value of the
second or third based on the value of the first.
|
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65
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TIR$C_OPR_REDEF (Redefine Symbol to Current Location)
|
This command is used only in the creation of shareable images. Data for
the command consists of a symbol name in standard name format, that is,
1 count byte followed by a variable-length (1 to 31 bytes) ASCII
string. The value of the symbol, as listed in the shareable image's
symbol table, is made equal to the value of the current location
counter (at the time the command is processed). Values of the symbol
within the image itself are not affected by the command. The value is
not assigned until after all image binary has been written to the image
output file. If no binary is generated (or is aborted), the value is
not assigned. The symbol is also made universal.
|
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66
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TIR$C_OPR_DFLIT (Define a Literal)
|
Data is a 1-byte field that indicates the literal (0 to 255) to be
defined. The literal is assigned the value of the top longword on the
stack, which is removed upon completion of the command. Note that this
command does not stack a result.
|
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67--79
|
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Reserved.
|
A.4.4 Control Commands
Control commands manipulate the linker's location counter.
Table A-6 lists the control commands and related codes, together
with a brief description of each command.
Table A-6 Control Commands
| Code |
Command |
Description |
|
80
|
TIR$C_CTL_SETRB (Set Relocation Base)
|
The top longword on the stack is placed into the location counter and
then removed from the stack.
|
|
81
|
TIR$C_CTL_AUGRB (Augment Relocation Base)
|
Data consists of a signed longword. The value of this longword is added
to the current location counter.
|
|
82
1
|
TIR$C_CTL_DFLOC (Define Location)
|
The value of the top longword on the stack is used as an index. The
value of the current location counter is then saved under this index.
Upon completion of the command, the top longword is removed from the
stack.
|
|
83
1
|
TIR$C_CTL_STLOC (Set Location)
|
The value of the top longword on the stack is an index (from a previous
Define Location command) that is used to locate a previously saved
location counter. The value of the previously saved location counter is
then set as the value of the current location counter. Upon completion
of the command, the top longword is removed from the stack.
|
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84
1
|
TIR$C_CTL_STKDL (Stack Debug)
|
The value of the top longword on the stack is an index (from a previous
Define Location command). The top longword is removed from the stack,
and the saved location counter, located by means of the index, is
placed on top of the stack.
|
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85--127
|
|
Reserved.
|
1This command is legal only in debugger information (DBG)
and traceback information (TBT) records. For each object module, a list
of debugger indexes is kept. These commands operate on the list for the
object module in which the DBG or TBT record occurs.
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