diff options
author | Ralf Baechle <ralf@linux-mips.org> | 2000-02-23 00:40:54 +0000 |
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committer | Ralf Baechle <ralf@linux-mips.org> | 2000-02-23 00:40:54 +0000 |
commit | 529c593ece216e4aaffd36bd940cb94f1fa63129 (patch) | |
tree | 78f1c0b805f5656aa7b0417a043c5346f700a2cf /arch/ia64/lib/copy_page.S | |
parent | 0bd079751d25808d1972baee5c4eaa1db2227257 (diff) |
Merge with 2.3.43. I did ignore all modifications to the qlogicisp.c
driver due to the Origin A64 hacks.
Diffstat (limited to 'arch/ia64/lib/copy_page.S')
-rw-r--r-- | arch/ia64/lib/copy_page.S | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/arch/ia64/lib/copy_page.S b/arch/ia64/lib/copy_page.S new file mode 100644 index 000000000..0a956e5a2 --- /dev/null +++ b/arch/ia64/lib/copy_page.S @@ -0,0 +1,87 @@ +/* + * + * Optimized version of the standard copy_page() function + * + * Based on comments from ddd. Try not to overflow write buffer. + * + * Inputs: + * in0: address of target page + * in1: address of source page + * Output: + * no return value + * + * Copyright (C) 1999 Hewlett-Packard Co + * Copyright (C) 1999 Stephane Eranian <eranian@hpl.hp.com> + */ +#include <asm/page.h> + +#define lcount r16 +#define saved_pr r17 +#define saved_lc r18 +#define saved_pfs r19 +#define src1 r20 +#define src2 r21 +#define tgt1 r22 +#define tgt2 r23 + + .text + .psr abi64 + .psr lsb + .lsb + + .align 32 + .global copy_page + .proc copy_page + +copy_page: + alloc saved_pfs=ar.pfs,10,0,0,8 // we need 6 roatating (8 minimum) + // + 2 input + + .rotr t1[4], t2[4] // our 2 pipelines with depth of 4 each + + mov saved_lc=ar.lc // save ar.lc ahead of time + mov saved_pr=pr // rotating predicates are preserved + // resgisters we must save. + mov src1=in1 // initialize 1st stream source + adds src2=8,in1 // initialize 2nd stream source + mov lcount=PAGE_SIZE/16-1 // as many 16bytes as there are on a page + // -1 is because br.ctop is repeat/until + + adds tgt2=8,in0 // initialize 2nd stream target + mov tgt1=in0 // initialize 1st stream target + ;; + mov pr.rot=1<<16 // pr16=1 & pr[17-63]=0 , 63 not modified + + mov ar.lc=lcount // set loop counter + mov ar.ec=4 // ar.ec must match pipeline depth + ;; + + // We need to preload the n-1 stages of the pipeline (n=depth). + // We do this during the "prolog" of the loop: we execute + // n-1 times the "load" bundle. Then both loads & stores are + // enabled until we reach the end of the last word of the page + // on the load side. Then, we enter the epilogue (controlled by ec) + // where we just do the stores and no loads n-1 times : drain the pipe. + // + // The initialization of the prolog is done via the predicate registers: + // the choice of pr19 DEPENDS on the depth of the pipeline (n). + // When lc > 0 pr63=1 and it is fed back into pr16 and pr16-pr62 + // are then shifted right at every iteration, + // Thus by initializing pr16=1 and pr17-19=0 (19=16+4-1) before the loop + // we get pr19=1 after 4 iterations (n in our case). + // +1: // engage loop now, let the magic happen... +(p16) ld8 t1[0]=[src1],16 // new data on top of pipeline in 1st stream +(p16) ld8 t2[0]=[src2],16 // new data on top of pipeline in 2nd stream + nop.i 0x0 +(p19) st8 [tgt1]=t1[3],16 // store top of 1st pipeline +(p19) st8 [tgt2]=t2[3],16 // store top of 2nd pipeline + br.ctop.dptk.few 1b // once lc==0, ec-- & p16=0 + // stores but no loads anymore + ;; + mov pr=saved_pr,0xffffffffffff0000 // restore predicates + mov ar.pfs=saved_pfs // restore ar.ec + mov ar.lc=saved_lc // restore saved lc + br.ret.sptk.few rp // bye... + + .endp copy_page |