AtariWiki V3.1: 6502 Coding Algorithms Macro Library
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6502 Coding Algorithms Macro Library, version 1Carsten Strotmann created this page on Fri Feb 03 15:21:13 GMT 2023:<br /><hr /><br /><p>General Information <br />
Author: Andrew John Jacobs <br />
Published: 1999 <br />
</p>
<p>This file contains a number of useful 6502
algorithms for number, string and memory
operations. The code is written in the form of
macros rather than subroutines to make them
more flexible.
</p>
<p>The routines in the library assume that 16 and
32 bit numbers are represented in little endian
order, that is the least significant byte in
the lowest memory location, so that they can
be applied to addresses as well as pure
numbers.
</p>
<p>The string routines assume that they are
working with null terminated 'C' style strings.
</p>
<p>The main routines sacrifice code size for speed
and are coded without any iteration. Compact
versions which use iteration are provided for
some algorithms and have the same name as the
original routine with a 'C' suffix (eg. _XFR32
=> _XFR32C).
</p>
<p>Some of the macros use 65SC02 instructions for
speed or to reduce the amount code generated if
the assembler will accept them.
</p>
<p>Where possible the macros detect optimizable
cases and generate more efficient code.
</p>
<p>Bugs & Enhancments:
</p>
<p>If you find a bug I missed or have a new
routine you would like to submit to the library
then mail me at:
</p>
<p>Andrew@obelisk.demon.co.uk
</p>
<p>fount at <a class="external" href="http://www.obelisk.demon.co.uk/6502/algorithms.html">http://www.obelisk.demon.co.uk/6502/algorithms.html</a><img class="outlink" src="/wiki/images/out.png" alt="" />
</p>
<hr />
<pre>
NOLIST
;------------------------------------------------
; 6502 Standard Macro Library
;------------------------------------------------
; Copyright (C),1999 Andrew John Jacobs.
; All rights reserved.
;------------------------------------------------
;------------------------------------------------
; Revision History:
;
; 16-Aug-99 AJJ Initial version.
;
; 14-Nov-01 AJJ Finally got around to filling in
; some missing comments.
;
;------------------------------------------------
; Notes:
;
; This file contains a number of useful 6502
; algorithms for number, string and memory
; operations. The code is written in the form of
; macros rather than subroutines to make them
; more flexible.
;
; The routines in the library assume that 16 and
; 32 bit numbers are represented in little endian
; order, that is the least significant byte in
; the lowest memory location, so that they can
; be applied to addresses as well as pure
; numbers.
;
; The string routines assume that they are
; working with null terminated 'C' style strings.
;
; The main routines sacrifice code size for speed
; and are coded without any iteration. Compact
; versions which use iteration are provided for
; some algorithms and have the same name as the
; original routine with a 'C' suffix (eg. _XFR32
; => _XFR32C).
;
; Some of the macros use 65SC02 instructions for
; speed or to reduce the amount code generated if
; the assembler will accept them.
;
; Where possible the macros detect optimizable
; cases and generate more efficient code.
;
; Bugs & Enhancments:
;
; If you find a bug I missed or have a new
; routine you would like to submit to the library
; then mail me at:
;
; Andrew@obelisk.demon.co.uk
PAGE
;------------------------------------------------
; Basic Operations
;------------------------------------------------
; Clear 2 bytes of memory at any location by
; setting it to zero. If 65SC02 instructions are
; available then STZ is used.
;
; On exit: A = ??, X & Y are unchanged.
IF __65SC02__
_CLR16 MACRO MEM
STZ MEM+0
STZ MEM+1
ENDM
ELSE
_CLR16 MACRO MEM
LDA #0
STA MEM+0
STA MEM+1
ENDM
ENDIF
; Clear 4 bytes of memory at any location by
; setting it to zero. If 65SC02 instructions are
; available then STZ is used.
;
; On exit: A = ??, X & Y are unchanged.
IF __65SC02__
_CLR32 MACRO MEM
STZ MEM+0
STZ MEM+1
STZ MEM+2
STZ MEM+3
ENDM
ELSE
_CLR32 MACRO MEM
LDA #0
STA MEM+0
STA MEM+1
STA MEM+2
STA MEM+3
ENDM
ENDIF
; Clear 4 bytes of memory at any location by
; setting it to zero iteratively. If 65SC02
; instructions are available then STZ is used.
;
; On exit: A = ??, X = $FF, Y is unchanged.
IF __65SC02__
_CLR32C MACRO MEM
LDX #3
_LOOP\? STZ MEM,X
DEX
BPL _LOOP\?
ENDM
ELSE
_CLR32C MACRO MEM
LDA #0
LDX #3
_LOOP\? STA MEM,X
DEX
BPL _LOOP\?
ENDM
ENDIF
; Transfer 2 bytes of memory from one location to
; another using the accumulator. The order in
; which the bytes are moved depends on the
; relative positions of SRC and DST. If SRC and
; DST are the same then no code is generated.
;
; On exit: A = ??, X & Y are unchanged.
_XFR16 MACRO SRC,DST
IF SRC != DST
IF SRC > DST
LDA SRC+0
STA DST+0
LDA SRC+1
STA DST+1
ELSE
LDA SRC+1
STA DST+1
LDA SRC+0
STA DST+0
ENDIF
ENDIF
ENDM
; Transfer 4 bytes of memory from one location to
; another using the accumulator. The order in
; which the bytes are moved depends on the
; relative positions of SRC and DST. If SRC and
; DST are the same then no code is generated.
;
; On exit: A = ??, X & Y are unchanged.
_XFR32 MACRO SRC,DST
IF SRC != DST
IF SRC > DST
LDA SRC+0
STA DST+0
LDA SRC+1
STA DST+1
LDA SRC+2
STA DST+2
LDA SRC+3
STA DST+3
ELSE
LDA SRC+3
STA DST+3
LDA SRC+2
STA DST+2
LDA SRC+1
STA DST+1
LDA SRC+0
STA DST+0
ENDIF
ENDIF
ENDM
; Transfer 4 bytes of memory from one location to
; another iteratively using the accumulator. The
; transfer may fail if SRC and DST overlap. If
; SRC and DST are the same then no code is
; generated.
;
; On exit: A = ??, X = $FF, Y is unchanged.
_XFR32C MACRO SRC,DST
IF SRC != DST
LDX #3
_LOOP\? LDA SRC,X
STA DST,X
DEX
BPL _LOOP\?
ENDIF
ENDM
; Set the value of a 16 bit location DST with
; the given constant value.
;
; On exit: A = ??, X & Y unchanged.
_SET16I MACRO NUM,DST
IF NUM != 0
LDA #LO NUM
STA DST+0
LDA #HI NUM
STA DST+1
ELSE
_CLR16 DST
ENDIF
PAGE
;------------------------------------------------
; Logical Operations
;------------------------------------------------
; Calculate the logical NOT of the 16 bit value
; at location VLA and stores it in location RES.
;
; On exit: A = ??, X & Y are unchanged.
_NOT16 MACRO VLA,RES
LDA VLA+0
EOR #$FF
STA RES+0
LDA VLA+1
EOR #$FF
STA RES+1
ENDM
; Calculate the logical NOT of the 32 bit value
; at location VLA and stores it in location RES.
;
; On exit: A = ??, X & Y are unchanged.
_NOT32 MACRO VLA,RES
LDA VLA+0
EOR #$FF
STA RES+0
LDA VLA+1
EOR #$FF
STA RES+1
LDA VLA+2
EOR #$FF
STA RES+2
LDA VLA+3
EOR #$FF
STA RES+3
ENDM
; Calculate the logical NOT of the 32 bit value
; at location VLA iteratively and stores it in
; location RES.
;
; On exit: A = ??, X = $FF, Y are unchanged.
_NOT32C MACRO VLA,RES
LDX #3
_LOOP\? LDA VLA,X
EOR #$FF
STA RES,X
DEX
BPL _LOOP\?
ENDM
; Calculate the logical OR of the two 16 bit
; values at locations VLA and VLB. The result is
; stored in location RES. If VLA and VLB are the
; same the macro expands to a _XFR16.
;
; On exit: A = ??, X & Y are unchanged.
_ORA16 MACRO VLA,VLB,RES
IF VLA != VLB
LDA VLA+0
ORA VLB+0
STA RES+0
LDA VLA+1
ORA VLB+1
STA RES+1
ELSE
_XFR16 VLA,RES
ENDIF
ENDM
; Calculate the logical OR of a 16 value at
; location VLA with a constant value and
; store the result at location RES.
;
; On exit: A = ??, X & Y are unchanged.
_ORA16I MACRO VLA,NUM,RES
LDA VLA+0
ORA #LO NUM
STA RES+0
LDA VLA+1
ORA #HI NUM
STA RES+1
ENDM
; Calculate the logical OR of the two 32 bit
; values at locations VLA and VLB. The result is
; stored in location RES. If VLA and VLB are the
; same the macro expands to a _XFR32.
;
; On exit: A = ??, X & Y are unchanged.
_ORA32 MACRO VLA,VLB,RES
IF VLA != VLB
LDA VLA+0
ORA VLB+0
STA RES+0
LDA VLA+1
ORA VLB+1
STA RES+1
LDA VLA+2
ORA VLB+2
STA RES+2
LDA VLA+3
ORA VLB+3
STA RES+3
ELSE
_XFR32 VLA,RES
ENDIF
ENDM
; Calculate the logical OR of the two 32 bit
; values at locations VLA and VLB iteratively.
; The result is stored in location RES. If VLA
; and VLB are the same the macro expands to a
; _XFR32C.
;
; On exit: A = ??, X = $FF, Y is unchanged.
_ORA32C MACRO VLA,VLB,RES
IF VLA != VLB
LDX #3
_LOOP\? LDA VLA,X
ORA VLB,X
STA RES,X
DEX
BPL _LOOP\?
ELSE
_XFR32C VLA,RES
ENDIF
ENDM
; Calculate the logical AND of the two 16 bit
; values at locations VLA and VLB. The result is
; stored in location RES. If VLA and VLB are the
; same the macro expands to a _XFR16.
;
; On exit: A = ??, X & Y are unchanged.
_AND16 MACRO VLA,VLB,RES
IF VLA != VLB
LDA VLA+0
AND VLB+0
STA RES+0
LDA VLA+1
AND VLB+1
STA RES+1
ELSE
_XFR16 VLA,RES
ENDIF
ENDM
; Calculate the logical AND of a 16 value at
; location VLA with a constant value and
; store the result at location RES.
;
; On exit: A = ??, X & Y are unchanged.
_AND16I MACRO VLA,NUM,RES
LDA VLA+0
AND #LO NUM
STA RES+0
LDA VLA+1
AND #HI NUM
STA RES+1
ENDM
; Calculate the logical AND of the two 32 bit
; values at locations VLA and VLB. The result is
; stored in location RES. If VLA and VLB are the
; same the macro expands to a _XFR32.
;
; On exit: A = ??, X & Y are unchanged.
_AND32 MACRO VLA,VLB,RES
IF VLA != VLB
LDA VLA+0
AND VLB+0
STA RES+0
LDA VLA+1
AND VLB+1
STA RES+1
LDA VLA+2
AND VLB+2
STA RES+2
LDA VLA+3
AND VLB+3
STA RES+3
ELSE
_XFR32 VLA,RES
ENDIF
ENDM
; Calculate the logical AND of the two 32 bit
; values at locations VLA and VLB iteratively.
; The result is stored in location RES. If VLA
; and VLB are the same the macro expands to a
; _XFR32C.
;
; On exit: A = ??, X = $FF, Y is unchanged.
_AND32C MACRO VLA,VLB,RES
IF VLA != VLB
LDX #3
_LOOP\? LDA VLA,X
AND VLB,X
STA RES,X
DEX
BPL _LOOP\?
ELSE
_XFR32C VLA,RES
ENDIF
ENDM
; Calculate the exclusive OR of the two 16 bit
; values at locations VLA and VLB. The result is
; stored in location RES. If VLA and VLB are the
; same the macro expands to a _CLR16.
;
; On exit: A = ??, X & Y are unchanged.
_EOR16 MACRO VLA,VLB,RES
IF VLA != VLB
LDA VLA+0
EOR VLB+0
STA RES+0
LDA VLA+1
EOR VLB+1
STA RES+1
ELSE
_CLR16 RES
ENDIF
ENDM
; Calculate the exclusive OR of a 16 value at
; location VLA with a constant value and
; store the result at location RES.
;
; On exit: A = ??, X & Y are unchanged.
_EOR16I MACRO VLA,NUM,RES
LDA VLA+0
EOR #LO NUM
STA RES+0
LDA VLA+1
EOR #HI NUM
STA RES+1
ENDM
; Calculate the exclusive OR of the two 32 bit
; values at locations VLA and VLB. The result is
; stored in location RES. If VLA and VLB are the
; same the macro expands to a _CLR32.
;
; On exit: A = ??, X & Y are unchanged.
_EOR32 MACRO VLA,VLB,RES
IF VLA != VLB
LDA VLA+0
EOR VLB+0
STA RES+0
LDA VLA+1
EOR VLB+1
STA RES+1
LDA VLA+2
EOR VLB+2
STA RES+2
LDA VLA+3
EOR VLB+3
STA RES+3
ELSE
_CLR32 RES
ENDIF
ENDM
; Calculate the exclusive OR of the two 32 bit
; values at locations VLA and VLB iteratively.
; The result is stored in location RES. If VLA
; and VLB are the same the macro expands to a
; _XFR32C.
;
; On exit: A = ??, X = $FF, Y is unchanged.
_EOR32C MACRO VLA,VLB,RES
IF VLA != VLB
LDX #3
_LOOP\? LDA VLA,X
EOR VLB,X
STA RES,X
DEX
BPL _LOOP\?
ELSE
_CLR32C RES
ENDIF
ENDM
PAGE
;------------------------------------------------
; Shift Operations
;------------------------------------------------
; Perform an arithmetic shift left on the 16 bit
; number at location VLA and store the result at
; location RES. If VLA and RES are the same then
; the operation is applied directly to the memory
; otherwise it is done in the accumulator.
;
; On exit: A = ??, X & Y are unchanged.
_ASL16 MACRO VLA,RES
IF VLA != RES
LDA VLA+0
ASL A
STA RES+0
LDA VLA+1
ROL A
STA RES+1
ELSE
ASL VLA+0
ROL VLA+1
ENDIF
ENDM
; Perform an arithmetic shift left on the 32 bit
; number at location VLA and store the result at
; location RES. If VLA and RES are the same then
; the operation is applied directly to the memory
; otherwise it is done in the accumulator.
;
; On exit: A = ??, X & Y are unchanged.
_ASL32 MACRO VLA,RES
IF VLA != RES
LDA VLA+0
ASL A
STA RES+0
LDA VLA+1
ROL A
STA RES+1
LDA VLA+2
ROL A
STA RES+2
LDA VLA+3
ROL A
STA RES+3
ELSE
ASL VLA+0
ROL VLA+1
ROL VLA+2
ROL VLA+3
ENDIF
ENDM
; Perform a left rotation on the 16 bit number at
; location VLA and store the result at location
; RES. If VLA and RES are the same then the
; operation is applied directly to the memory,
; otherwise it is done in the accumulator.
;
; On exit: A = ??, X & Y are unchanged.
_ROL16 MACRO VLA,RES
IF VLA != RES
LDA VLA+0
ROL A
STA RES+0
LDA VLA+1
ROL A
STA RES+1
ELSE
ROL VLA+0
ROL VLA+1
ENDIF
ENDM
; Perform a left rotation on the 32 bit number at
; location VLA and store the result at location
; RES. If VLA and RES are the same then the
; operation is applied directly to the memory,
; otherwise it is done in the accumulator.
;
; On exit: A = ??, X & Y are unchanged.
_ROL32 MACRO VLA,RES
IF VLA != RES
LDA VLA+0
ROL A
STA RES+0
LDA VLA+1
ROL A
STA RES+1
LDA VLA+2
ROL A
STA RES+2
LDA VLA+3
ROL A
STA RES+3
ELSE
ROL VLA+0
ROL VLA+1
ROL VLA+2
ROL VLA+3
ENDIF
ENDM
; Perform an logical shift right on the 16 bit
; number at location VLA and store the result at
; location RES. If VLA and RES are the same then
; the operation is applied directly to the memory
; otherwise it is done in the accumulator.
;
; On exit: A = ??, X & Y are unchanged.
_LSR16 MACRO VLA,RES
IF VLA != RES
LDA VLA+1
LSR A
STA RES+1
LDA VLA+0
ROR A
STA RES+0
ELSE
LSR VLA+1
ROR VLA+0
ENDIF
ENDM
; Perform an logical shift right on the 32 bit
; number at location VLA and store the result at
; location RES. If VLA and RES are the same then
; the operation is applied directly to the memory
; otherwise it is done in the accumulator.
;
; On exit: A = ??, X & Y are unchanged.
_LSR32 MACRO VLA,RES
IF VLA != RES
LDA VLA+3
LSR A
STA RES+3
LDA VLA+2
ROR A
STA RES+2
LDA VLA+1
ROR A
STA RES+1
LDA VLA+0
ROR A
STA RES+0
ELSE
LSR VLA+3
ROR VLA+2
ROR VLA+1
ROR VLA+0
ENDIF
ENDM
; Perform a right rotation on the 16 bit number
; at location VLA and store the result at
; location RES. If VLA and RES are the same then
; the operation is applied directly to the memory
; otherwise it is done in the accumulator.
;
; On exit: A = ??, X & Y are unchanged.
_ROR16 MACRO VLA,RES
IF VLA != RES
LDA VLA+1
ROR A
STA RES+1
LDA VLA+0
ROR A
STA RES+0
ELSE
ROR VLA+1
ROR VLA+0
ENDIF
ENDM
; Perform a right rotation on the 32 bit number
; at location VLA and store the result at
; location RES. If VLA and RES are the same then
; the operation is applied directly to the memory
; otherwise it is done in the accumulator.
;
; On exit: A = ??, X & Y are unchanged.
_ROR32 MACRO VLA,RES
IF VLA != RES
LDA VLA+3
ROR A
STA RES+3
LDA VLA+2
ROR A
STA RES+2
LDA VLA+1
ROR A
STA RES+1
LDA VLA+0
ROR A
STA RES+0
ELSE
ROR VLA+3
ROR VLA+2
ROR VLA+1
ROR VLA+0
ENDIF
ENDM
PAGE
;------------------------------------------------
; Arithmetic Operations
;------------------------------------------------
; Increment the 16 bit value at location MEM
; by one.
;
; On exit: A, X & Y are unchanged.
_INC16 MACRO MEM
INC MEM+0
BNE _DONE\?
INC MEM+1
_DONE\? EQU *
ENDM
; Increment the 32 bit value at location MEM
; by one.
;
; On exit: A, X & Y are unchanged.
_INC32 MACRO MEM
INC MEM+0
BNE _DONE\?
INC MEM+1
BNE _DONE\?
INC MEM+2
BNE _DONE\?
INC MEM+3
_DONE\? EQU *
ENDM
; Decrement the 16 bit value at location MEM
; by one.
;
; On exit: A = ??, X & Y are unchanged.
_DEC16 MACRO MEM
LDA MEM+0
BNE _DONE\?
DEC MEM+1
_DONE\? DEC MEM+0
ENDM
; Decrement the 32 bit value at location MEM
; by one.
;
; On exit: A = ??, X & Y are unchanged.
_DEC32 MACRO MEM
LDA MEM+0
BNE _DEC0\?
LDA MEM+1
BNE _DEC1\?
LDA MEM+2
BNE _DEC2\?
DEC MEM+3
_DEC2\? DEC MEM+2
_DEC1\? DEC MEM+1
_DEC0\? DEC MEM+0
ENDM
; Add two 16 bit numbers together and store the
; result in another memory location. RES may be
; the same as either VLA or VLB.
;
; On exit: A = ??, X & Y are unchanged.
_ADD16 MACRO VLA,VLB,RES
IF VLA != VLB
CLC
LDA VLA+0
ADC VLB+0
STA RES+0
LDA VLA+1
ADC VLB+1
STA RES+1
ELSE
_ASL16 VLA,RES
ENDIF
ENDM
; Add two 32 bit numbers together and store the
; result in another memory location. RES may be
; the same as either VLA or VLB.
;
; On exit: A = ??, X & Y are unchanged.
_ADD32 MACRO VLA,VLB,RES
IF VLA != VLB
CLC
LDA VLA+0
ADC VLB+0
STA RES+0
LDA VLA+1
ADC VLB+1
STA RES+1
LDA VLA+2
ADC VLB+2
STA RES+2
LDA VLA+3
ADC VLB+3
STA RES+3
ELSE
_ASL32 VLA,RES
ENDIF
ENDM
; Subtract two 16 bit numbers and store the
; result in another memory location. RES may be
; the same as VLA or VLB.
;
; On exit: A = ??, X & Y are unchanged.
_SUB16 MACRO VLA,VLB,RES
SEC
LDA VLA+0
SBC VLB+0
STA RES+0
LDA VLA+1
SBC VLB+1
STA RES+1
ENDM
; Subtract two 32 bit numbers and store the
; result in another memory location. RES may be
; the same as VLA or VLB.
;
; On exit: A = ??, X & Y are unchanged.
_SUB32 MACRO VLA,VLB,RES
SEC
LDA VLA+0
SBC VLB+0
STA RES+0
LDA VLA+1
SBC VLB+1
STA RES+1
LDA VLA+2
SBC VLB+2
STA RES+2
LDA VLA+3
SBC VLB+3
STA RES+3
ENDM
; Negate the signed 16 bit number at location VLA
; and stored the result at location RES. RES may
; be the same as VLA.
;
; On exit: A = ??, X & Y are unchanged.
_NEG16 MACRO VLA,RES
SEC
LDA #0
SBC VLA+0
STA RES+0
LDA #0
SBC VLA+1
STA RES+1
ENDM
; Negate the signed 32 bit number at location VLA
; and stored the result at location RES. RES may
; be the same as VLA.
;
; On exit: A = ??, X & Y are unchanged.
_NEG32 MACRO VLA,RES
SEC
LDA #0
SBC VLA+0
STA RES+0
LDA #0
SBC VLA+1
STA RES+1
LDA #0
SBC VLA+2
STA RES+2
LDA #0
SBC VLA+3
STA RES+3
ENDM
; Calculates the absolute value of signed 16 bit
; number at location VLA and stores it in the RES
; location. Less code is generated if VLA and RES
; are the same location. If 65SC02 instructions
; are available a BRA is used to shorten the
; generated code.
;
; On exit: A = ??, X & Y are unchanged.
_ABS16 MACRO VLA,RES
BIT VLA+0
IF VLA != RES
BPL _MOVE\?
_NEG16 VLA,RES
IF __65SC02__
BRA _DONE\?
ELSE
JMP _DONE\?
ENDIF
_MOVE\? EQU *
_XFR16 VLA,RES
ELSE
BPL _DONE\?
_NEG16 VLA,RES
ENDIF
_DONE\? EQU *
ENDM
; Calculates the absolute value of signed 32 bit
; number at location VLA and stores it in the RES
; location. Less code is generated if VLA and RES
; are the same location. If 65SC02 instructions
; are available a BRA is used to shorten the
; generated code.
;
; On exit: A = ??, X & Y are unchanged.
_ABS32 MACRO VLA,RES
BIT VLA+0
IF VLA != RES
BPL _MOVE\?
_NEG32 VLA,RES
IF __65SC02__
BRA _DONE\?
ELSE
JMP _DONE\?
ENDIF
_MOVE\? EQU *
_XFR32 VLA,RES
ELSE
BPL _DONE\?
_NEG32 VLA,RES
ENDIF
_DONE\? EQU *
ENDM
; Calculate the 16 bit product of two 16 bit
; unsigned numbers. Any overflow during the
; calculation is lost. The number at location
; VLA is destroyed.
;
; On exit: A = ??, X = $FF, Y is unchanged.
_MUL16 MACRO VLA,VLB,RES
_CLR16 RES
LDX #16
_LOOP\? EQU *
_ASL16 RES,RES
_ASL16 VLA,VLA
BCC _NEXT\?
_ADD16 VLB,RES,RES
_NEXT\? DEX
BPL _LOOP\?
ENDM
; Calculate the 32 bit product of two 16 bit
; unsigned numbers. The number at location VLA
; is destroyed.
;
; On exit: A = ??, X = $FF, Y is unchanged.
_MUL16X MACRO VLA,VLB,RES
_CLR32 RES
LDX #16
_LOOP\? EQU *
_ASL32 RES,RES
_ASL16 VLA,VLA
BCC _NEXT\?
_ADD16 VLB,RES,RES
BCC _NEXT\?
_INC16 RES+2
_NEXT\? EQU *
DEX
BPL _LOOP\?
ENDM
; Calculate the 32 bit product of two 32 bit
; unsigned numbers. Any overflow during the
; calculation is lost. The number at location
; VLA is destroyed.
;
; On exit: A = ??, X = $FF, Y is unchanged.
_MUL32 MACRO VLA,VLB,RES
_CLR32 RES
LDX #32
_LOOP\? EQU *
_ASL32 RES,RES
_ASL32 VLA,VLA
BCC _NEXT\?
_ADD32 VLB,RES,RES
_NEXT\? EQU *
DEX
BPL _LOOP\?
ENDM
; These two macros write the code necessary
; to multiply a 16 bit at location VLA by
; a 16 bit constant NUM and store the 16 bit
; result in location RES.
;
; On exit: A = ??, X & Y unchanged.
_MUL16I MACRO VLA,NUM,RES
IF NUM = 1
_XFR16 VLA,RES
ELSE
_CLR16 RES
__MUL16I VLA,NUM,RES
ENDIF
ENDM
__MUL16I MACRO VLA,NUM,RES
IF NUM & $FFFE
__MUL16I VLA,(NUM/2),RES
_ASL16 RES,RES
ENDIF
IF NUM & $0001
_ADD16 VLA,RES,RES
ENDIF
ENDM
; Divide the 16 bit number at location VLA
; by the 16 bit number at location VLB
; leaving the 16 bit quotient at QUO and
; the 16 bit remainder in REM. The value in
; location VLA is destroyed.
;
; On exit: A = ??, X = $FF, Y is unchanged.
_DIV16 MACRO VLA,VLB,QUO,REM
_CLR16 REM
LDX #16
_LOOP\? EQU *
_ASL16 VLA,VLA
_ROL16 REM,REM
_SUB16 REM,VLB,REM
BCS _NEXT\?
_ADD16 REM,VLB,REM
_NEXT\? EQU *
_ROL16 QUO,QUO
DEX
BPL _LOOP\?
ENDM
; Divide the 32 bit number at location VLA
; by the 16 bit number at location VLB
; leaving the 16 bit quotient at QUO and
; the 16 bit remainder in REM. The value in
; location VLA is destroyed.
;
; On exit: A = ??, X = $FF, Y is unchanged.
_DIV16X MACRO VLA,VLB,QUO,REM
_CLR16 REM
LDX #32
_LOOP\? EQU *
_ASL32 VLA,VLA
_ROL16 REM,REM
_SUB16 REM,VLB,REM
BCS _NEXT\?
_ADD16 REM,VLB,REM
_NEXT\? EQU *
_ROL16 QUO,QUO
DEX
BPL _LOOP\?
ENDM
; Divide the 32 bit number at location VLA
; by the 32 bit number at location VLB
; leaving the 32 bit quotient at QUO and
; the 32 bit remainder in REM. The value in
; location VLA is destroyed.
;
; On exit: A = ??, X = $FF, Y is unchanged.
_DIV32 MACRO VLA,VLB,QUO,REM
_CLR32 REM
LDX #32
_LOOP\? EQU *
_ASL32 VLA,VLA
_ROL32 REM,REM
_SUB32 REM,VLB,REM
BCS _NEXT\?
_ADD32 REM,VLB,REM
_NEXT\? EQU *
_ROL32 QUO,QUO
DEX
BPL _LOOP\?
ENDM
PAGE
;------------------------------------------------
; Comparative Operations
;------------------------------------------------
; Compares two 16 bit values in memory areas VLA
; and VLB. The comparison starts with the most
; significant bytes and returns as soon as a
; difference is detected.
;
; On exit: A = ??, X & Y are unchanged.
_CMP16 MACRO VLA,VLB
LDA VLA+1
CMP VLB+1
BNE _DONE\?
LDA VLA+0
CMP VLB+0
_DONE\? EQU *
ENDM
; Compares two 32 bit values in memory areas VLA
; and VLB. The comparison starts with the most
; significant bytes and returns as soon as a
; difference is detected.
;
; On exit: A = ??, X & Y are unchanged.
_CMP32 MACRO VLA,VLB
LDA VLA+3
CMP VLB+3
BNE _DONE\?
LDA VLA+2
CMP VLB+2
BNE _DONE\?
LDA VLA+1
CMP VLB+1
BNE _DONE\?
LDA VLA+0
CMP VLB+0
_DONE\? EQU *
ENDM
PAGE
;------------------------------------------------
; Memory Operations
;------------------------------------------------
; Transfers a block of memory from one place to
; another by copying the bytes starting at the
; front of the block and going forward. SRC and
; DST are destroyed during the copy.
;
; On exit: A, X & Y = ??.
_MEMFWD MACRO SRC,DST,LEN
LDY #0
LDX LEN+1
BEQ _FRAG\?
_PAGE\? LDA (SRC),Y
STA (DST),Y
INY
BNE _PAGE\?
INC SRC+1
INC DST+1
DEX
BNE _PAGE\?
_FRAG\? CPY LEN+0
BEQ _DONE\?
LDA (SRC),Y
STA (DST),Y
INY
BNE _FRAG\?
_DONE\? EQU *
ENDM
; Transfers a block of memory from one place to
; another by copying the bytes starting at the
; end of the block and going backwards.
_MEMREV MACRO SRC,DST,LEN
NOP
ENDM
; Tranfers a block of memory from one location to
; another. Depending on the relative positions of
; the blocks an appropriate transfer method is
; used.
_MEMCPY MACRO SRC,DST,LEN
_CMP16 SRC,DST
BCC _SAFE\?
_MEMFWD SRC,DST,LEN
IF __65SC02__
BRA _DONE\?
ELSE
JMP _DONE\?
ENDIF
_SAFE\? _MEMREV SRC,DST,LEN
_DONE\? EQU *
ENDM
PAGE
;------------------------------------------------
; String Operations
;------------------------------------------------
; Calculates length of a null terminated string
; by searching for its end. The address of the
; string in STR is destroyed during the search.
;
; On exit: A & Y = ??, X is unchanged.
_STRLEN MACRO STR,LEN
LDY #0
STY LEN+1
_LOOP\? LDA (STR),Y
BEQ _DONE\?
INY
BNE _LOOP\?
INC LEN+1
INC STR+1
IF __65SC02__
BRA _LOOP\?
ELSE
JMP _LOOP\?
ENDIF
_DONE\? STY LEN+0
ENDM
; Copies a null terminated string from one memory
; location to another. The source and destination
; addresses are destroyed during the copy process.
;
; On exit: A & Y = ??, X is unchanged.
_STRCPY MACRO SRC,DST
LDY #0
_LOOP\? LDA (SRC),Y
STA (DST),Y
BEQ _DONE\?
INY
BNE _LOOP\?
INC SRC+1
INC DST+1
IF __65SC02__
BRA _LOOP\?
ELSE
JMP _LOOP\?
ENDIF
_DONE\? EQU *
ENDM
;
_STRCMP MACRO VLA,VLB
LDY #0
_LOOP\? LDA (VLA),Y
CMP (VLB),Y
BNE _DONE\?
LDA (VLA),Y
BEQ _DONE\?
INY
BNE _LOOP\?
INC VLA+1
INC VLB+1
IF __65SC02__
BRA _LOOP\?
ELSE
JMP _LOOP\?
ENDIF
_DONE\? EQU *
ENDM
;
_STRNCMP MACRO VLA,VLB,LEN
ENDM
LIST
</pre>
<p />Fri, 03 Feb 2023 15:21:13 GMT