2023-12-02 03:39:40 +00:00
|
|
|
* Copyright (c) 2023 Stephen Heumann
|
|
|
|
|
*
|
2024-06-27 02:46:58 +00:00
|
|
|
* Permission to use, copy, modify, and/or distribute this software for any
|
2023-12-02 03:39:40 +00:00
|
|
|
* purpose with or without fee is hereby granted, provided that the above
|
|
|
|
|
* copyright notice and this permission notice appear in all copies.
|
|
|
|
|
*
|
|
|
|
|
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
|
|
|
|
|
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
|
|
|
|
|
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
|
|
|
|
|
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
|
|
|
|
|
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
|
|
|
|
|
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
|
|
|
|
|
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
|
|
|
|
|
|
|
|
|
|
* Direct page locations
|
|
|
|
|
i gequ 0
|
|
|
|
|
j gequ 1
|
|
|
|
|
S gequ 2
|
|
|
|
|
|
|
|
|
|
* Do one step of the RC4 pseudo-random generation algorithm.
|
|
|
|
|
* Call with DP = RC4 context structure, and short M/X.
|
|
|
|
|
RC4_PRGA start
|
|
|
|
|
;i := (i + 1) mod 256
|
|
|
|
|
inc i
|
|
|
|
|
|
|
|
|
|
;j := (j + S[i]) mod 256
|
|
|
|
|
ldx i
|
|
|
|
|
clc
|
|
|
|
|
lda S,x
|
|
|
|
|
tay
|
|
|
|
|
adc j
|
|
|
|
|
sta j
|
|
|
|
|
|
|
|
|
|
;swap values of S[i] and S[j]
|
|
|
|
|
tax
|
|
|
|
|
lda S,x
|
|
|
|
|
|
|
|
|
|
ldx i
|
|
|
|
|
sta S,x
|
|
|
|
|
|
|
|
|
|
ldx j
|
|
|
|
|
tya
|
|
|
|
|
sta S,x
|
|
|
|
|
|
|
|
|
|
;temp := (S[i] + S[j]) mod 256
|
|
|
|
|
ldx i
|
|
|
|
|
clc
|
|
|
|
|
adc S,x
|
|
|
|
|
|
|
|
|
|
;return S[temp]
|
|
|
|
|
tax
|
|
|
|
|
lda S,x
|
|
|
|
|
|
|
|
|
|
rtl
|
|
|
|
|
end
|
