// disclaimed.
// ====================================================================
-.ident "rc4-ia64.S, Version 1.1"
+.ident "rc4-ia64.S, Version 2.0"
.ident "IA-64 ISA artwork by Andy Polyakov <appro@fy.chalmers.se>"
// What's wrong with compiler generated code? Because of the nature of
// Legitimate "collisions" do occur within every 256^2 bytes window.
// Fortunately there're enough free instruction slots to keep prior
// reference to key[x+1], detect "collision" and compensate for it.
-// All this without sacrificing a single clock cycle:-)
-// Furthermore. In order to compress loop body to the minimum, I chose
-// to deploy deposit instruction, which substitutes for the whole
-// key->data+((x&255)<<log2(sizeof(key->data[0]))). This unfortunately
-// requires key->data to be aligned at sizeof(key->data) boundary.
-// This is why you'll find "RC4_INT pad[512-256-2];" addenum to RC4_KEY
-// and "d=(RC4_INT *)(((size_t)(d+255))&~(sizeof(key->data)-1));" in
-// rc4_skey.c [and rc4_enc.c, where it's retained for debugging
-// purposes]. Throughput is ~210MBps on 900MHz CPU, which is is >3x
-// faster than gcc generated code and +30% - if compared to HP-UX C.
-// Unrolling loop below should give >30% on top of that...
+// All this without sacrificing a single clock cycle:-) Throughput is
+// ~210MBps on 900MHz CPU, which is is >3x faster than gcc generated
+// code and +30% - if compared to HP-UX C. Unrolling loop below should
+// give >30% on top of that...
.text
.explicit
# define ADDP add
#endif
+#ifndef SZ
#define SZ 4 // this is set to sizeof(RC4_INT)
+#endif
// SZ==4 seems to be optimal. At least SZ==8 is not any faster, not for
// assembler implementation, while SZ==1 code is ~30% slower.
#if SZ==1 // RC4_INT is unsigned char
ADDP out=0,in3
brp.loop.imp .Ltop,.Lexit-16 };;
{ .mmi; LDKEY yy=[key] // load key->y
- add ksch=(255+1)*SZ,key // as ksch will be used with
- // deposit instruction only,
- // I don't have to &~255...
+ add ksch=SZ,key
mov ar.lc=in1 }
{ .mmi; mov key_y[1]=r0 // guarantee inequality
// in first iteration
add xx=1,xx
mov pr.rot=1<<16 };;
{ .mii; nop.m 0
- dep key_x[1]=xx,ksch,OFF,8
+ dep key_x[1]=xx,r0,OFF,8
mov ar.ec=3 };; // note that epilogue counter
// is off by 1. I compensate
// for this at exit...
.Ltop:
-// The loop is scheduled for 3*(n+2) spin-rate on Itanium 2, which
+// The loop is scheduled for 4*(n+2) spin-rate on Itanium 2, which
// theoretically gives asymptotic performance of clock frequency
-// divided by 3 bytes per seconds, or 500MBps on 1.5GHz CPU. Measured
-// performance however is distinctly lower than 1/4:-( The culplrit
-// seems to be *(out++)=dat, which inadvertently splits the bundle,
-// even though there is M-port available... Unrolling is due...
-// Unrolled loop should collect output with variable shift instruction
-// in order to avoid starvation for integer shifter... It should be
-// possible to get pretty close to theoretical peak...
-{ .mmi; (p16) LDKEY tx[0]=[key_x[1]] // tx=key[xx]
- (p17) LDKEY ty[0]=[key_y[1]] // ty=key[yy]
- (p18) dep rnd[1]=rnd[1],ksch,OFF,8} // &key[(tx+ty)&255]
+// divided by 4 bytes per seconds, or 400MBps on 1.6GHz CPU. This is
+// for sizeof(RC4_INT)==4. For smaller RC4_INT STKEY inadvertently
+// splits the last bundle and you end up with 5*n spin-rate:-(
+// Originally the loop was scheduled for 3*n and relied on key
+// schedule to be aligned at 256*sizeof(RC4_INT) boundary. But
+// *(out++)=dat, which maps to st1, had same effect [inadvertent
+// bundle split] and holded the loop back. Rescheduling for 4*n
+// made it possible to eliminate dependence on specific alignment
+// and allow OpenSSH keep "abusing" our API. Reaching for 3*n would
+// require unrolling, sticking to variable shift instruction for
+// collecting output [to avoid starvation for integer shifter] and
+// copying of key schedule to controlled place in stack [so that
+// deposit instruction can serve as substitute for whole
+// key->data+((x&255)<<log2(sizeof(key->data[0])))]...
{ .mmi; (p19) st1 [out]=dat[3],1 // *(out++)=dat
(p16) add xx=1,xx // x++
- (p16) cmp.ne.unc p20,p21=key_x[1],key_y[1] };;
+ (p18) dep rnd[1]=rnd[1],r0,OFF,8 } // ((tx+ty)&255)<<OFF
+{ .mmi; (p16) add key_x[1]=ksch,key_x[1] // &key[xx&255]
+ (p17) add key_y[1]=ksch,key_y[1] };; // &key[yy&255]
+{ .mmi; (p16) LDKEY tx[0]=[key_x[1]] // tx=key[xx]
+ (p17) LDKEY ty[0]=[key_y[1]] // ty=key[yy]
+ (p16) dep key_x[0]=xx,r0,OFF,8 } // (xx&255)<<OFF
+{ .mmi; (p18) add rnd[1]=ksch,rnd[1] // &key[(tx+ty)&255]
+ (p16) cmp.ne.unc p20,p21=key_x[1],key_y[1] };;
{ .mmi; (p18) LDKEY rnd[1]=[rnd[1]] // rnd=key[(tx+ty)&255]
- (p16) ld1 dat[0]=[inp],1 // dat=*(inp++)
- (p16) dep key_x[0]=xx,ksch,OFF,8 } // &key[xx&255]
+ (p16) ld1 dat[0]=[inp],1 } // dat=*(inp++)
.pred.rel "mutex",p20,p21
{ .mmi; (p21) add yy=yy,tx[1] // (p16)
(p20) add yy=yy,tx[0] // (p16) y+=tx
(p21) mov tx[0]=tx[1] };; // (p16)
{ .mmi; (p17) STKEY [key_y[1]]=tx[1] // key[yy]=tx
(p17) STKEY [key_x[2]]=ty[0] // key[xx]=ty
- (p16) dep key_y[0]=yy,ksch,OFF,8 } // &key[yy&255]
+ (p16) dep key_y[0]=yy,r0,OFF,8 } // &key[yy&255]
{ .mmb; (p17) add rnd[0]=tx[1],ty[0] // tx+=ty
(p18) xor dat[2]=dat[2],rnd[1] // dat^=rnd
br.ctop.sptk .Ltop };;
projects / oweals / openssl.git / commitdiff