Highly compressible representation of test pattern data

• US 5,905,986 A
• Filed: 01/07/1997
• Issued: 05/18/1999
• Est. Priority Date: 01/07/1997
• Status: Expired due to Term

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Rohrbaugh, John G, Rearick, Jeff
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): HO, RUAY L
• Application Number:
  US08/779,760
• Time in Patent Office: 861 Days
• Field of Search: 707/1-10, 707/100-104, 707/200-206, 707/506, 341/51, 341/64, 341/67, 341/87, 257/503, 257/537
• US Class Current: 1/1
• CPC Class Codes: G11C 29/10 Test algorithms, e.g. memory scan [MScan] algorithms; Test patterns, e.g. checkerboard patterns
• CPC Class Codes: G11C 29/56004 Pattern generation
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation

Abstract

A method for more efficient handling of data used in testing electronic integrated circuits and boards consisting of specifying data in a flat tabular format. Signal data are contained in columns and cycle data are contained in rows. Any given signal in a cycle will typically be a "0" or "1". If a signal does not change from one cycle to the next, the character "0" or "1" is replaced in the latter cycle by the dot "." character. As a result of the "." character replacements, the data is much more highly compressible by standard compression software than before, thus requiring less storage space for the data.

Claims

1. A method for altering a data file within a computer system wherein said altering allows said data file to be stored in less storage space within said computer system, said method comprising the steps of:

(a) sequentially processing each data record in said data file to substitute a pattern character for each character in said data record when said character in said data record is identical to a correspondingly located character in a previous data record, sequentially processed immediately previous to said data record, wherein an altered data file is created; and

(b) restoring said altered data file by sequentially processing each altered data record in said altered data file to substitute a correspondingly located character found in said altered data record, sequentially processed immediately previous to each said altered data record, for each pattern character in each said altered data record of said altered data file.

2. The method of claim 1 further comprising the following step (a0), performed before step (a):

(a0) processing a first data record of said data file without altering said first data record.

3. A method for altering a data file within a computer system wherein said altering allows said data file to be stored in less storage space within said computer system, said method comprising the steps of:

(a) sequentially processing each data record in said date file to substitute a pattern character for each character in said data record when said character in said data record is identical to a correspondingly located character in a previous data record, sequentially processed immediately previous to said data record, wherein an altered data file is created; and

(b) compressing said altered data file and storing said compressed altered data file on a storage device.

4. The method of claim 3 further comprising the steps of:

(c) retrieving said compressed altered data file from said storage device and decompressing said compressed altered data file wherein a recreated altered data file is created; and

(d) restoring said recreated altered data file by sequentially processing each recreated altered data record in said recreated altered data file to substitute a correspondingly located character found in a previous recreated altered data record, sequentially processed immediately previous to each said recreated altered data record of said recreated altered data file for each pattern character in said recreated altered data record of said recreated altered data file.

5. The method of claim 4 further comprising the following step (d1), performed before step (d):

(d1) processing a first recreated altered data record of said recreated altered data file without altering said first recreated altered data record.

6. The method of claim 3 further comprising the following step (a0), performed before step (a):

(a0) processing a first data record of said data file without altering said first data record.

7. A method for altering a data file within a computer system to create an altered data file, wherein said altering allows said altered data file to be stored in less storage space within said computer system, said method comprising the steps of:

(a) reading a first data record of said data file into a computer memory;

(b) writing said first data record to a storage device;

(c) copying said first data record to a history area to create a history record;

(d) reading a next data record from said data file into said computer memory;

(e) comparing each character of said next data record with each character of said history record;

(f) when a character of said next data record matches a correspondingly located character of said history record, writing a predetermined pattern character to an output record at a location in said output record corresponding to a location of said character of said next data record;

(g) when a character of said next data record does not match a correspondingly located character of said history record, writing said character of said next data record to said output record at a location in said output record corresponding to a location of said character of said next data record;

(h) after all characters have been processed by step (f) and step (g), writing said output record to said storage device;

(i) copying said next data record to said history area as said history record; and

(j) repeating steps (d) through (i) for each of said next data records in said data file to create said altered data file.

8. The method of claim 7 further comprising the steps of:

(k) reading a first altered data record of said altered data file into a computer memory;

(l) writing said first altered data record to said storage device;

(m) copying said first altered data record to a history area to create an altered history record;

(n) reading a next altered data record from said altered data file into said computer memory;

(o) comparing each character of said next altered data record with each character of said altered history record;

(p) when a character of said next altered data record is a predetermined pattern character, writing a correspondingly located character of said altered history record to an output record at a location in said output record corresponding to a location of said predetermined pattern character;

(q) when a character of said next altered data record is not said predetermined pattern character, writing said character of said next altered data record to said output record at said location in said output record corresponding to said location of said character of said next altered data record;

(r) after all characters of said next data records have been processed by step (p) and step (q), writing said output record to said storage device;

(s) copying said output record to said history area as said history record; and

(t) repeating steps (n) through (s) for each of said next altered data records in said data file to restore said altered data file.

9. The method of claim 7 further comprising the steps of:

(k) compressing said altered data file to create a compressed altered data file and storing said compressed altered data file on said storage device.

10. The method of claim 9 further comprising the steps of:

(l) retrieving said compressed altered data file from said storage device;

(m) decompressing said compressed altered data file;

(n) reading a first altered data record of said altered data file into said computer memory;

(o) writing said first altered data record to said storage device;

(p) copying said first altered data record to a history area to create an altered history record;

(q) reading a next altered data record from said altered data file into said computer memory;

(r) comparing each character of said next altered data record with each character of said altered history record;

(s) when a character of said next altered data record is a predetermined pattern character, writing a correspondingly located character of said altered history record to an output record at a location in said output record corresponding to a location of said predetermined pattern character;

(t) when a character of said next altered data record is not a said predetermined pattern character, writing said character of said next altered data record to said output record at said location in said output record corresponding to said location of said character of said next altered data record;

(u) after all characters of said next altered data record have been processed by step (s) and step (t), writing said output record to said storage device;

(v) copying said output record to said history area as said history record;

(w) repeating steps (q) through (v) for each of said next altered data records in said data file wherein a restored altered data file is created; and

(x) applying said restored altered data file to a device under test.

11. A method for altering a test pattern data file within a computer system allowing said altered test pattern data file to be stored in less storage space within said computer system, said method comprising the steps of:

(a) processing a first data record of said test pattern data file without altering said first data record;

(b) sequentially processing each remaining data record in said test pattern data file to substitute a predetermined pattern character for each character in said each remaining data record in said test pattern data file when said character in each said remaining data record is identical to a correspondingly located character in a previous data record, processed immediately previous to said each remaining data record in said test pattern data file, wherein an altered test pattern data file is created;

(c) processing a first altered data record of said altered test pattern data file without altering said first altered data record;

(d) sequentially processing each remaining altered data record in said test pattern data file to substitute a correspondingly located character found in a previous data record, sequentially processed immediately previous to said remaining altered data record of said altered test pattern data file for each predetermined pattern character in said each remaining altered data record of said altered data file, wherein a restored test pattern data file is created; and

(e) applying said restored test pattern data file to a device under test.

12. The method of claim 11 further comprising the following steps (b1) and (b2) performed after step (b) and prior to step (c):

(b1) compressing said altered test pattern data file to create a compressed altered test pattern data file and storing said compressed altered test pattern data file on said storage device; and

(b2) retrieving said compressed altered test pattern data file from said storage device and decompressing said compressed altered test pattern data file.