GATE CSE 1992 | Question: 01,viii

Question

The purpose of instruction location counter in an assembler is _______

Comments

The purpose of instruction location counter in an assembler is _______

I think for Back patching related work.

Refer ->

https://stackoverflow.com/questions/15984671/what-does-backpatching-mean

http://www.keil.com/support/man/docs/a51/a51_wp_locationcounter.htm

Answer 1

Each section of an assembler language program has a location counter used to assign storage addresses to your program's statements. As the instructions of a source module are being assembled, the location counter keeps track of the current location in storage.

Comments

What is the use of assigning storage location to each statement?

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Labelled jumps maybe.

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http://www.keil.com/support/man/docs/a51/a51_wp_locationcounter.htm

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https://www.ibm.com/support/knowledgecenter/en/ssw_aix_71/com.ibm.aix.alangref/idalangref_loc_counter.htm

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In intermediate code generation stage of a compiler we often need to execute "jump" instructions to places in the code that don't exist yet. To deal with this type of cases a target label is inserted for that instruction. A marker nonterminal in the production rule causes the semantic action to pick up.

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What is the use of assigning storage location to each statement? 

i think this processes done in pass 1 phase of compiler after that generate data values  defined by byte ,word and perform processing of assembler directives not done in pass 1. 

@Bikram

@Arjun

Answer 2

$\underline{\textbf{Answer:}\Rightarrow}$

$\underline{\textbf{Explanation:}\Rightarrow}$

Purposes of instruction location counter in an assembler are as follows:

• The location counter checks whether the next available memory location can be assigned within the present (current) segment, such as code, or data. In other words, it contains the offset of the instruction or the data being assembled.
• By default, the location counter starts from zero and increment by one when each byte of memory is allocated. But the location counter may be changed using the $\mathbf{ORG}$ statement.

• To start the location counter at a particular offset address $\color{blue}{\text{org assembler directive}}$ may be used.

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  http://et.engr.iupui.edu/~skoskie/ECE362/lecture_notes/LN2_html/text8.html

• http://www.keil.com/support/man/docs/a51/a51_wp_locationcounter.htm

Answer 3

same use as instruction pointer in recursion

Answer 4

The purpose of the instruction location counter (LC) in an assembler is to keep track of the memory address or location assigned to the next instruction or data in the program being assembled.