[openfirmware] r1501 - cpu/x86

[svn at openfirmware.info]

Author: wmb
Date: 2009-11-25 21:27:12 +0100 (Wed, 25 Nov 2009)
New Revision: 1501

Added:
   cpu/x86/adler32.fth
Log:
Added Adler32 checksum routine to source tree; unused at present.


Added: cpu/x86/adler32.fth
===================================================================
--- cpu/x86/adler32.fth	                        (rev 0)
+++ cpu/x86/adler32.fth	2009-11-25 20:27:12 UTC (rev 1501)
@@ -0,0 +1,57 @@
+\ See license at end of file
+purpose: Adler-32 checksum (used in zlib compression)
+
+code adler32  ( adr len -- adler )
+   0 [sp]  bp  xchg   \ bp: len  and save bp
+   4 [sp]  si  xchg   \ si: adr  and save si
+   bp cx mov          \ cx: len
+   di push            \ Save di
+   d# 65521 # di mov  \ MOD_ADLER
+
+   bx bx xor          \ A
+   bx inc             \ bx: A=1
+   bp bp xor          \ bp: B=0
+   begin
+      ax ax xor
+      al lods         \ ax: data[index]
+      bx ax add       \ ax: A + data[index]
+      dx dx xor       \ Clear high word of dividend
+      di  div         \ Remainder in dx
+      dx bx mov       \ bx: A = (A + data[index]) % MOD_ADLER
+      bx bp add       \ bp: B + A
+      dx dx xor       \ Clear high word of dividend
+      bp ax mov       \ ax: low word of dividend
+      di  div         \ Remainder in dx
+      dx bp mov       \ bp: B = (B + A) % MOD_ADLER
+   loopa
+   d# 16 # bp shl     \ bp: (B << 16)
+   bp bx or           \ bx: (B << 16) | A
+   di pop             \ Restore di
+   bp pop             \ Restore bp
+   si pop             \ Restore si
+   bx push            \ Return result
+c;
+
+\ LICENSE_BEGIN
+\ Copyright (c) 2006 FirmWorks
+\ 
+\ Permission is hereby granted, free of charge, to any person obtaining
+\ a copy of this software and associated documentation files (the
+\ "Software"), to deal in the Software without restriction, including
+\ without limitation the rights to use, copy, modify, merge, publish,
+\ distribute, sublicense, and/or sell copies of the Software, and to
+\ permit persons to whom the Software is furnished to do so, subject to
+\ the following conditions:
+\ 
+\ The above copyright notice and this permission notice shall be
+\ included in all copies or substantial portions of the Software.
+\ 
+\ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+\ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+\ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+\ NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+\ LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+\ OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+\ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+\
+\ LICENSE_END