Describes Christian Krüger's macro package for writing self modifying
assembler code.
+ <tag><htmlurl url="specialmath.html" name="specialmath.html"></tag>
+ Library for speed optimized math functions.
+
<tag><url name="6502 Binary Relocation Format document"
url="http://www.6502.org/users/andre/o65/fileformat.html"></tag>
Describes the o65 file format that is used for dynamically loadable modules
--- /dev/null
+<!doctype linuxdoc system>
+
+<article>
+<title>Special math functions
+<author>Christian Krüger
+
+<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>
--- /dev/null
+/*****************************************************************************/
+/* */
+/* specialmath.h */
+/* */
+/* Optimized math routines for special usages */
+/* */
+/* */
+/* */
+/* (C) 2019 Christian 'Irgendwer' Krueger */
+/* */
+/* This software is provided 'as-is', without any expressed or implied */
+/* warranty. In no event will the authors be held liable for any damages */
+/* arising from the use of this software. */
+/* */
+/* Permission is granted to anyone to use this software for any purpose, */
+/* including commercial applications, and to alter it and redistribute it */
+/* freely, subject to the following restrictions: */
+/* */
+/* 1. The origin of this software must not be misrepresented; you must not */
+/* claim that you wrote the original software. If you use this software */
+/* in a product, an acknowledgment in the product documentation would be */
+/* appreciated but is not required. */
+/* 2. Altered source versions must be plainly marked as such, and must not */
+/* be misrepresented as being the original software. */
+/* 3. This notice may not be removed or altered from any source */
+/* distribution. */
+/* */
+/*****************************************************************************/
+
+#ifndef _SPECIALMATH_H
+#define _SPECIALMATH_H
+
+
+/* Multiply an 8 bit unsigned value by 20 and return the 16 bit unsigned result */
+
+unsigned int __fastcall__ mul20(unsigned char value);
+
+
+/* Multiply an 8 bit unsigned value by 40 and return the 16 bit unsigned result */
+
+unsigned int __fastcall__ mul40(unsigned char value);
+
+
+
+/* End of specialmath.h */
+#endif
mouse \
runtime \
serial \
+ specialmath \
tgi \
zlib
.export _cputcxy, _cputc
.export plot, cputdirect, putchar
- .import gotoxy, mul40
+ .import gotoxy, _mul40
.importzp tmp4,ptr4
.import _revflag,setcursor
sta (OLDADR),y
lda ROWCRS
- jsr mul40 ; destroys tmp4
- clc
+ jsr _mul40 ; destroys tmp4, carry is cleared
adc SAVMSC ; add start of screen memory
sta ptr4
txa
.export _mouse_txt_callbacks
.importzp tmp4
- .import mul40,loc_tmp
+ .import _mul40
.importzp mouse_txt_char ; screen code of mouse cursor
.include "atari.inc"
; Move the mouse cursor y position to the value in A/X.
movey:
- tax
- ldy tmp4 ; mul40 uses tmp4
- lda loc_tmp ; and this local variable
- pha
- txa ; get parameter back
+ ldy tmp4 ; mul40 uses tmp4, save in Y
lsr a ; convert y position to character line
lsr a
lsr a
- jsr mul40
- clc
+ jsr _mul40 ; carry is cleared by _mul40
adc SAVMSC
sta scrptr
txa
adc SAVMSC+1
sta scrptr+1
- pla
- sta loc_tmp
- sty tmp4
+ sty tmp4 ; restore tmp4
rts
+++ /dev/null
-;
-; Christian Groessler, June 2000
-;
-; mul40
-; multiplies A by 40 and returns result in AX
-; uses tmp4
-
- .importzp tmp4
- .export mul40,loc_tmp
-
-.proc mul40
-
- ldx #0
- stx tmp4
- sta loc_tmp
- asl a
- rol tmp4
- asl a
- rol tmp4 ; val * 4
- adc loc_tmp
- bcc L1
- inc tmp4 ; val * 5
-L1: asl a
- rol tmp4 ; val * 10
- asl a
- rol tmp4
- asl a
- rol tmp4 ; val * 40
- ldx tmp4
- rts
-
-.endproc
-
- .bss
-loc_tmp:.res 1
.include "atari.inc"
.importzp tmp1,tmp4,ptr1,ptr2
- .import mul40,_clrscr
+ .import _mul40,_clrscr
.export __scroll
.proc __scroll
sta ptr2+1
lda tmp1
- jsr mul40
+ jsr _mul40
sta tmp4
lda ptr2
sec
jmp _clrscr
;multiply by 40 (xsize)
-up_ok: jsr mul40
- clc
+up_ok: jsr _mul40 ; carry is cleared by _mul40
adc SAVMSC ; add start of screen mem
sta ptr2
txa
; cursor handling, internal function
.include "atari.inc"
- .import cursor,mul40
+ .import cursor,_mul40
.export setcursor
.proc setcursor
sta (OLDADR),y
lda ROWCRS
- jsr mul40
- clc
+ jsr _mul40 ; function leaves with carry clear!
adc SAVMSC ; add start of screen memory
sta OLDADR
txa
.export _cputcxy, _cputc
.export plot, cputdirect, putchar
- .import gotoxy, mul20
+ .import gotoxy, _mul20
.importzp ptr4
.import setcursor
pha ; save char
lda ROWCRS_5200
- jsr mul20 ; destroys tmp4
- clc
+ jsr _mul20 ; destroys tmp4, carry is cleared
adc SAVMSC ; add start of screen memory
sta ptr4
txa
+++ /dev/null
-;
-; Christian Groessler, April 2014
-;
-; mul20
-; multiplies A by 20 and returns result in AX
-; uses tmp4
-
- .importzp tmp4
- .export mul20,loc_tmp
-
-.proc mul20
-
- ldx #0
- stx tmp4
- sta loc_tmp
- asl a
- rol tmp4
- asl a
- rol tmp4 ; val * 4
- adc loc_tmp
- bcc L1
- inc tmp4 ; val * 5
-L1: asl a
- rol tmp4 ; val * 10
- asl a
- rol tmp4 ; val * 20
- ldx tmp4
- rts
-
-.endproc
-
- .bss
-loc_tmp:.res 1
--- /dev/null
+; mul20.s
+;
+; This file is part of
+; cc65 - a freeware C compiler for 6502 based systems
+;
+; https://github.com/cc65/cc65
+;
+; See "LICENSE" file for legal information.
+;
+;
+; unsigned int __fastcall__ mul20(unsigned char value);
+;
+; REMARKS: Function is defined to return with carry-flag cleared
+
+
+ .importzp tmp4
+ .export _mul20
+
+.proc _mul20 ; = 30 bytes, 41/46 cycles
+
+ sta tmp4 ; remember value for later addition...
+ ldx #0 ; clear high-byte
+ asl a ; * 2
+ bcc mul4 ; high-byte affected?
+ ldx #2 ; this will be the 1st high-bit soon...
+
+mul4: asl a ; * 4
+ bcc mul5 ; high-byte affected?
+ inx ; => yes, apply to 0 high-bit
+ clc ; prepare addition
+
+mul5: adc tmp4 ; * 5
+ bcc mul10 ; high-byte affected?
+ inx ; yes, correct...
+
+mul10: stx tmp4 ; continue with classic shifting...
+
+ asl a ; * 10
+ rol tmp4
+
+ asl a ; * 20
+ rol tmp4
+
+ ldx tmp4 ; deliver high-byte in X
+ rts
+
+.endproc
--- /dev/null
+; mul40.s
+;
+; This file is part of
+; cc65 - a freeware C compiler for 6502 based systems
+;
+; https://github.com/cc65/cc65
+;
+; See "LICENSE" file for legal information.
+;
+;
+; unsigned int __fastcall__ mul40(unsigned char value);
+;
+; REMARKS: Function is defined to return with carry-flag cleared
+
+
+ .importzp tmp4
+ .export _mul40
+
+.proc _mul40 ; = 33 bytes, 48/53 cycles
+
+ sta tmp4 ; remember value for later addition...
+ ldx #0 ; clear high-byte
+ asl a ; * 2
+ bcc mul4 ; high-byte affected?
+ ldx #2 ; this will be the 1st high-bit soon...
+
+mul4: asl a ; * 4
+ bcc mul5 ; high-byte affected?
+ inx ; => yes, apply to 0 high-bit
+ clc ; prepare addition
+
+mul5: adc tmp4 ; * 5
+ bcc mul10 ; high-byte affected?
+ inx ; yes, correct...
+
+mul10: stx tmp4 ; continue with classic shifting...
+
+ asl a ; * 10
+ rol tmp4
+
+ asl a ; * 20
+ rol tmp4
+
+ asl a ; * 40
+ rol tmp4
+
+ ldx tmp4 ; deliver high-byte in X
+ rts
+
+.endproc
--- /dev/null
+#include <specialmath.h>
+#include "unittest.h"
+
+TEST
+{
+ unsigned i;
+
+ for (i=0; i < 256; ++i)
+ {
+ ASSERT_AreEqual(i*20, mul20(i), "%u", "Invalid 'mul20(%u)' calculation!" COMMA i);
+ }
+
+ for (i=0; i < 256; ++i)
+ {
+ ASSERT_AreEqual(i*40, mul40(i), "%u", "Invalid 'mul40(%u)' calculation!" COMMA i);
+ }
+}
+ENDTEST
projects / cc65 / commitdiff