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Cross Reference Recording in Assembly Listings

IP.com Disclosure Number: IPCOM000075665D
Original Publication Date: 1971-Oct-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 72K

Publishing Venue

IBM

Related People

Witt, I: AUTHOR

Abstract

Cross references in assembly listings are a useful tool for debugging programs. One of the main purposes is to find the instructions by which fields or registers have been altered. According to the method described, the use of cross-reference listings is facilitated by recording or flagging all instructions by which registers (and fields) have been changed, even if these registers have not been defined symbolically. For this purpose, pseudo-symbols are used: bC.REG0, bG.REG1, bG.REG2...bG.REG15, bFL.REG0, bFL.REG2, bFL.REG4, bFL.REG6.

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Cross Reference Recording in Assembly Listings

Cross references in assembly listings are a useful tool for debugging programs. One of the main purposes is to find the instructions by which fields or registers have been altered. According to the method described, the use of cross-reference listings is facilitated by recording or flagging all instructions by which registers (and fields) have been changed, even if these registers have not been defined symbolically. For this purpose, pseudo-symbols are used: bC.REG0, bG.REG1, bG.REG2...bG.REG15, bFL.REG0, bFL.REG2, bFL.REG4, bFL.REG6.

The generated Op-Code is investigated by the use of a translate table, which contains the displacements to a branch vector table of 11 routines (the examples refer to the IBM System/360):

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where "flag operand n" means: a bit provided for flagging in the cross-reference record is set to one for a symbol (D1, D2, R1, R3) of an operand which is altered by this instruction, and where "create pseudo record" means: create a cross- reference record with pseudo-symbol bG.REGn (or bFL.REGn), and set the flag bit provided in the cross-reference record to one. The routines are addressed by the use of a translate tab in which the ordinate and the abscissa are assigned to the first two characters of the instructions, to be recorded. An example of such a table is shown below.

The cross-reference entries are sorted and listed in the last phase. The pseudo-symbols will be listed precedin...