PelROOT

The Pelletron-Linac data analysis tools for ROOT

adac

This document describes the structure of the acquisition system programming interface. ADAC+ is used to compile the EVS program into a binary code that can be easily understood by the CAMAC driver. Every time a CAMAC module generates a LAM (Look-At-Me) signal an interruption is generated in the computer. This interruptions is processed by the CAMAC driver in the computer and the corresponding instructions are processed.

This document is divided as follow:

• HOW TO ASSEMBLE A PROGRAM
• STRUCTURE OF THE PROGRAM
• BASIC INSTRUCTION LIST AND DEFINITIONS
• MACRO INSTRUCTION LIST AND DEFINITIONS
• REGISTERS and OPERATORS
• PRE-COMPILER DIRECTIVES
• DIRECTIVES TO THE ASSEMBLER ("EQUATE", LOOP, ENDLOOP)
• ASSEMBLY-TIME VARIABLES
• STATEMENT LABELS
• SYNTAX RULES
• PROGRAMMING EXAMPLE

How to assemble a program

The commands to assembler and disassemble a program are:

• adac [FILE NAME] - to compile a program
• tadac4096 [FILE NAME] - the same as above

[FILE NAME] may or may not contain the extension (.EVS for the source code and .EVP for a compiled program). The command adac+ will produce the following files:

• [FILE NAME].EVO - The compiled program

Structure of the program

The data acquisition program is divided into two main sections:

• configuration
  • This section configures the CAMAC modules in order to make them ready for data acquisition.
• event loop
  • When a LAM signal is generated in the CAMAC electronic and sent to the computer, the event is processed by this part of the program. The event loop section should read the CAMAC modules, process the information and send the data in the correct format to the output.

The configuration section runs only when the program is loaded into the CAMAC driver. The event loop section runs every time an event is processed. The user should remember that a LAM signal should be generated by some CAMAC module in order to tell the computer to process an event. Therefore, there should be a command in this part of the program that enables the LAM feature in one of the CAMAC modules.

IMPORTANT NOTE: In general, the LAM signal is generated after the event is processed by the CAMAC module. If there are slower modules than the one used for the LAM generation it may be possible that the data in the slower modules can not be ready to be transferred to the computer, making, sometimes, the data unusable.

The configuration and event loop blocks are separated by the INIT statement. The INIT statement tells the computer where the event loop instructions begin. The END statements tells the computer where the event loop block finishes. A basic structure of a program is:

    ...
    ...
    CONFIGURATION INSTRUCTIONS
    ...
    ...

    INIT

    ...
    ...
    EVENT LOOP INSTRUCTIONS
    ...
    ...

    END

Basic instruction list and definitions

• NOP
  • Do nothing
• BRU DEST
  • Branch to Destination - DEST is a label or an absolute address in the code. I strongly suggest to use labels as destinations because it is very easy to miscalculate absolute addresses by hand
• SPB DEST
  • STORE POSITION and BRANCH - Similar to CALL in Fortran. DEST is a label or absolute address in the same form as for BRU. The main difference between BRU and SPB is the fact that SPB tells the computer to remember its address. The system stores up to 100 nested SPB addresses. If more than 100 SPB are called, without the corresponding command BRUR, each subsequent SPB command will act like a simple BRU command
• BRUR
  • Return from subroutine called by SPB. If there is no SPB address stored in the memory, nothing is done. BRUR returns to the NEXT instruction just after the last SPB command was called
• DLAY #
  • Wait for #*(0.1 micro-sec) up to 409.6 micro-sec. The argument has to be a number or an assembly-time variable. Registers are not allowed in this command.
• INIT
  • Set the startup of the event loop. Sets the point of return for the CAMAC configuration part of the program
• END
  • Set the end of the event loop. Exits the loop or the CAMAC configuration, if called
• RTRN
  • Exit the event loop or the CAMAC configuration, if called
• NAF N, A, F
  • Do NAF - result is stored in register CA
• OUT [R]
  • Output Register [R]. [R] can also be a number or an assembly-time variable.
• MERG [T], [R]
  • Merge (AND) the 12-16 bits of the register [T] into register [R] and send [R] to the output. [T] can also be a number or an assembly-time variable. [R] has to be a valid register.
• MOV [T], [R]
  • Move content of register [T] to register [R]. [T] can also be a number or an assembly-time variable. [R] has to be a valid register.
• SKIP [R].OP.[T]
  • This command skips the next instruction if the logical operation defined by the operator .OP. between the registers [R] and [T] are satisfied. [R] has to be an valid register. [T] can also be a number or an assembly time variable.

Macro instruction list and definitions

• IF([R].OP.[T]) ADDR
  • Go to ADDR if the logical operation defined by the operator .OP. between the registers [R] and [T] are satisfied. [R] has to be an valid register. [T] can also be a number or an assembly time variable. ADDR can be either a label in the code or an absolute address.
    
    This command is expanded into the following basic instructions:

          SKIP [R].IO.[T]
          BRU ADDR
    

    where .IO. is the inverse operator of .OP. For example, the inverse operator of .GT. is .LE.
• ROUT N, A, F
  • Similar to NAF but also sends the register to the output. See NAF for more details.
    
    This command is expanded into the following basic instructions:

          NAF N, A, F 
          OUT 
    

Registers and operators

There are 3 main registers available. The main difference between the different registers is their size. The registers are ZEROED in the beginning of each run but they are NOT zeroed from one event to the other. The registers are:

• PAT - 16 bits register. Often used to store CAMAC module bit patterns
• EX - 16 bits register. General use
• CA - 12 bits register. General use

Please note that the CA register is smaller than the others.

The operators are FORTRAN style operators and are:

• [R].ANY.[T] - Compare and bit a bit and the result is true if at least one of the bits match
• [R].NONE.[T] - Compare and bit a bit and the result is true if at none of the bits match
• [R].GT.[T] - Returns true if is greater than
• [R].LT.[T] - Returns true if is smaller than
• [R].GE.[T] - Returns true if is greater or equal than
• [R].LE.[T] - Returns true if is smaller or equal than
• [R].EQ.[T] - Returns true if is equal to
• [R].NE.[T] - Returns true if is different than

Pre-compiler directives

Pre compiler directives are used to set some CAMAC parameters or label the compiled program. When running the acquisition system with the SPMRoot program there is no need for such directives. These directives are mainly used by the old SPM acquisition system. See the SPM documentation for more information.

The main pre-compiler directives are:

• KAUX = #
• CSYS = #
• CREM = #
• CAUX = #
• NAUX = #
• NSHD = #
• PGM$