+# void RC4(RC4_KEY *key,size_t len,const unsigned char *inp,unsigned char *out);
+&function_begin("RC4");
+ &mov ($dat,&wparam(0)); # load key schedule pointer
+ &mov ($ty, &wparam(1)); # load len
+ &mov ($inp,&wparam(2)); # load inp
+ &mov ($out,&wparam(3)); # load out
+
+ &xor ($xx,$xx); # avoid partial register stalls
+ &xor ($yy,$yy);
+
+ &cmp ($ty,0); # safety net
+ &je (&label("abort"));
+
+ &mov (&LB($xx),&BP(0,$dat)); # load key->x
+ &mov (&LB($yy),&BP(4,$dat)); # load key->y
+ &add ($dat,8);
+
+ &lea ($tx,&DWP(0,$inp,$ty));
+ &sub ($out,$inp); # re-bias out
+ &mov (&wparam(1),$tx); # save input+len
+
+ &inc (&LB($xx));
+
+ # detect compressed key schedule...
+ &cmp (&DWP(256,$dat),-1);
+ &je (&label("RC4_CHAR"));
+
+ &mov ($tx,&DWP(0,$dat,$xx,4));
+
+ &and ($ty,-4); # how many 4-byte chunks?
+ &jz (&label("loop1"));
+
+ &mov (&wparam(3),$out); # $out as accumulator in these loops
+ if ($x86only) {
+ &jmp (&label("go4loop4"));
+ } else {
+ &test ($ty,-8);
+ &jz (&label("go4loop4"));
+
+ &picmeup($out,"OPENSSL_ia32cap_P");
+ &bt (&DWP(0,$out),26); # check SSE2 bit [could have been MMX]
+ &jnc (&label("go4loop4"));
+
+ &mov ($out,&wparam(3)) if (!$alt);
+ &movd ("mm7",&wparam(3)) if ($alt);
+ &and ($ty,-8);
+ &lea ($ty,&DWP(-8,$inp,$ty));
+ &mov (&DWP(-4,$dat),$ty); # save input+(len/8)*8-8
+
+ &$RC4_loop_mmx(-1);
+ &jmp(&label("loop_mmx_enter"));
+
+ &set_label("loop_mmx",16);
+ &$RC4_loop_mmx(0);
+ &set_label("loop_mmx_enter");
+ for ($i=1;$i<8;$i++) { &$RC4_loop_mmx($i); }
+ &mov ($ty,$yy);
+ &xor ($yy,$yy); # this is second key to Core2
+ &mov (&LB($yy),&LB($ty)); # and Westmere performance...
+ &cmp ($inp,&DWP(-4,$dat));
+ &lea ($inp,&DWP(8,$inp));
+ &jb (&label("loop_mmx"));
+
+ if ($alt) {
+ &movd ($out,"mm7");
+ &pxor ("mm2","mm0");
+ &psllq ("mm1",8);
+ &pxor ("mm1","mm2");
+ &movq (&QWP(-8,$out,$inp),"mm1");
+ } else {
+ &psllq ("mm1",56);
+ &pxor ("mm2","mm1");
+ &movq (&QWP(-8,$out,$inp),"mm2");
+ }
+ &emms ();
+
+ &cmp ($inp,&wparam(1)); # compare to input+len
+ &je (&label("done"));
+ &jmp (&label("loop1"));
+ }
+
+&set_label("go4loop4",16);
+ &lea ($ty,&DWP(-4,$inp,$ty));
+ &mov (&wparam(2),$ty); # save input+(len/4)*4-4
+
+ &set_label("loop4");
+ for ($i=0;$i<4;$i++) { RC4_loop($i); }
+ &ror ($out,8);
+ &xor ($out,&DWP(0,$inp));
+ &cmp ($inp,&wparam(2)); # compare to input+(len/4)*4-4
+ &mov (&DWP(0,$tx,$inp),$out);# $tx holds re-biased out here
+ &lea ($inp,&DWP(4,$inp));
+ &mov ($tx,&DWP(0,$dat,$xx,4));
+ &jb (&label("loop4"));
+
+ &cmp ($inp,&wparam(1)); # compare to input+len
+ &je (&label("done"));
+ &mov ($out,&wparam(3)); # restore $out
+
+ &set_label("loop1",16);
+ &add (&LB($yy),&LB($tx));
+ &mov ($ty,&DWP(0,$dat,$yy,4));
+ &mov (&DWP(0,$dat,$yy,4),$tx);
+ &mov (&DWP(0,$dat,$xx,4),$ty);
+ &add ($ty,$tx);
+ &inc (&LB($xx));
+ &and ($ty,0xff);
+ &mov ($ty,&DWP(0,$dat,$ty,4));
+ &xor (&LB($ty),&BP(0,$inp));
+ &lea ($inp,&DWP(1,$inp));
+ &mov ($tx,&DWP(0,$dat,$xx,4));
+ &cmp ($inp,&wparam(1)); # compare to input+len
+ &mov (&BP(-1,$out,$inp),&LB($ty));
+ &jb (&label("loop1"));
+
+ &jmp (&label("done"));
+
+# this is essentially Intel P4 specific codepath...
+&set_label("RC4_CHAR",16);
+ &movz ($tx,&BP(0,$dat,$xx));