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Compression/Decompression of Font Patterns

IP.com Disclosure Number: IPCOM000059736D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 82K

Publishing Venue

IBM

Related People

Ishii, N: AUTHOR [+2]

Abstract

This article describes the generation or decompression of font patterns from the compressed form data including control bytes and data bytes. An 8 x 16 dot matrix, as shown in Figs. 1 and 2, is assigned for each character. Referring to Fig. 1, the first 8 x 8 dot matrix in the 8 x 16 character font pattern is generated from a control byte (a) and data bytes (b) - (f), and the second 8 x 8 dot matrix is generated from a control byte (g) and data bytes (h) - (k). The control bytes (a) and (g) indicate vertical arrangement of the sixteen 8-dot horizontal slices or blocks. The "0" bit in the control byte indicates that an 8-dot horizontal slice includes all "0" bits, and the "1" bit in the control byte indicates that a data byte following the control byte will be mapped as an 8-dot horizontal slice.

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Compression/Decompression of Font Patterns

This article describes the generation or decompression of font patterns from the compressed form data including control bytes and data bytes. An 8 x 16 dot matrix, as shown in Figs. 1 and 2, is assigned for each character. Referring to Fig. 1, the first 8 x 8 dot matrix in the 8 x 16 character font pattern is generated from a control byte (a) and data bytes (b) - (f), and the second 8 x 8 dot matrix is generated from a control byte (g) and data bytes (h) - (k). The control bytes (a) and (g) indicate vertical arrangement of the sixteen 8-dot horizontal slices or blocks. The "0" bit in the control byte indicates that an 8-dot horizontal slice includes all "0" bits, and the "1" bit in the control byte indicates that a data byte following the control byte will be mapped as an 8-dot horizontal slice. The number of the data bytes which follow the control byte is equal to the number of "1" bits in the control byte. The data byte is mapped sequentially. Fig. 2 shows an alternative method for assembling the 8 x 16 dot matrix. Three kinds of control bytes are used. The control byte is identified by "1101" in the high nibble. The first type control byte (m) includes "0000" in the low nibble followed by one byte (q), and indicates that an 8-dot horizontal slice of all "0" bits is repeated by the number of times specified by the byte (q). The second type control byte (s) includes "0001" in the low nibble followed by a byte (t). The c...