xerox Display Stream Package Sep75 free download

File name Display_Stream_Package_Sep75.pdf

Display stream package September 3. 1975 1 Display stream package A library package is now available which provides a capability for display streams with considerably more flexihility than the current operating system streams. Additional features include multiple fonts. repositioning to any bit position in the current line (or, under proper circumstances, any line). selective erasing and polarity inversion, and better util ization of the availab'le bitmap space. The package consists of two files, DSTREAM and DHANX. In addition. the file DISP.D provides useful parameter and structure declarations. in particular the parameters lOCB and 105 mentioned below. DSTREAM is written in Bcpl and occupies about 2.4K (octal). DHANX is written in assembly language and occupies about .1K (octal). The package does not require any routines other than those in the operating system. 1. Creating a display stream CreateDstream(v, nl, ds, options) creates a display stream. V is the samB 4-word vector currently used for creating display streams through the operating system (see section 3.2.3 of the 0.5. manual). but, unlike tile 0.5., CreateDstream requires that v be supplied and that v!O and v!l delimit a storage area. Nl is the number of 1 ines for the stream: it is completely independent of the amount of sflace supplied for bitmap and DCBs. Ds is a pointer to a h I 0 c k 0 r I [) S V/O r d s wh i c h will be use d to s tor e the s t ream. its elf. If ds is omitted. Cl'eateDstream will try to obtain such a block from the 0.5. using CHLAfES(v, DISPLAYOPErJ): tiltS procedure is not reCOrili11ended in lJi~~\'! of. '. IH:\ ')mall nt.lIllber of .displ(lY str'ea''1S provided by the O.S. Ine vaiue returned by CreateUstream is tile stream (dS if ds was supplied). The mlnlmum space for a display stream is lDCB