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Optimized mul20 & mul40 and extracted to new library.

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This commit is contained in:
IrgendwerA8
2019-03-21 15:59:45 +01:00
committed by Oliver Schmidt
parent fbf302e6cd
commit 399250a105
14 changed files with 216 additions and 92 deletions
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doc/specialmath.sgml Normal file
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<!doctype linuxdoc system>
<article>
<title>Special math functions
<author>Christian Kr&uuml;ger
<abstract>
This library provides functions for speed optimized math operations.
</abstract>
<!-- Table of contents -->
<toc>
<!-- Begin the document -->
<sect>Multiplication<p>
When accessing screen memory often a multiplication of the vertical position is needed to calculate
the target address. A quite common horizontal span for 8-bit systems is 20 or 40 bytes (beside e.g. 32 bytes, where the multiplication can be accomplished by shifting 5 times).
<p>
<tscreen><verb>
unsigned int __fastcall__ mul20(unsigned char value);
</verb></tscreen>
The 8 bit <tt>value</tt> is multiplied by 20 and returned as 16 bit value.
</p>
<p>
<tscreen><verb>
unsigned int __fastcall__ mul40(unsigned char value);
</verb></tscreen>
The 8 bit <tt>value</tt> is multiplied by 40 and returned as 16 bit value.
</p>
</article>