! ! Fast SH memcpy ! ! by Toshiyasu Morita (tm@netcom.com) ! hacked by J"orn Rernnecke (joern.rennecke@superh.com) ("o for o-umlaut) ! SH5 code Copyright 2002 SuperH Ltd. ! ! Entry: ARG0: destination pointer ! ARG1: source pointer ! ARG2: byte count ! ! Exit: RESULT: destination pointer ! any other registers in the range r0-r7: trashed ! ! Notes: Usually one wants to do small reads and write a longword, but ! unfortunately it is difficult in some cases to concatanate bytes ! into a longword on the SH, so this does a longword read and small ! writes. ! ! This implementation makes two assumptions about how it is called: ! ! 1.: If the byte count is nonzero, the address of the last byte to be ! copied is unsigned greater than the address of the first byte to ! be copied. This could be easily swapped for a signed comparison, ! but the algorithm used needs some comparison. ! ! 2.: When there are two or three bytes in the last word of an 11-or-more ! bytes memory chunk to b copied, the rest of the word can be read ! without side effects. ! This could be easily changed by increasing the minumum size of ! a fast memcpy and the amount subtracted from r7 before L_2l_loop be 2, ! however, this would cost a few extra cyles on average. ! For SHmedia, the assumption is that any quadword can be read in its ! enirety if at least one byte is included in the copy. /* Imported into Linux kernel by Richard Curnow. This is used to implement the __copy_user function in the general case, so it has to be a distinct function from intra-kernel memcpy to allow for exception fix-ups in the event that the user pointer is bad somewhere in the copy (e.g. due to running off the end of the vma). Note, this algorithm will be slightly wasteful in the case where the source and destination pointers are equally aligned, because the stlo/sthi pairs could then be merged back into single stores. If there are a lot of cache misses, this is probably offset by the stall lengths on the preloads. */ /* NOTE : Prefetches removed and allocos guarded by synco to avoid TAKum03020 * erratum. The first two prefetches are nop-ed out to avoid upsetting the * instruction counts used in the jump address calculation. * */ .section .text..SHmedia32,"ax" .little .balign 32 .global copy_user_memcpy .global copy_user_memcpy_end copy_user_memcpy: #define LDUAQ(P,O,D0,D1) ldlo.q P,O,D0; ldhi.q P,O+7,D1 #define STUAQ(P,O,D0,D1) stlo.q P,O,D0; sthi.q P,O+7,D1 #define LDUAL(P,O,D0,D1) ldlo.l P,O,D0; ldhi.l P,O+3,D1 #define STUAL(P,O,D0,D1) stlo.l P,O,D0; sthi.l P,O+3,D1 nop ! ld.b r3,0,r63 ! TAKum03020 pta/l Large,tr0 movi 25,r0 bgeu/u r4,r0,tr0 nsb r4,r0 shlli r0,5,r0 movi (L1-L0+63*32 + 1) & 0xffff,r1 sub r1, r0, r0 L0: ptrel r0,tr0 add r2,r4,r5 ptabs r18,tr1 add r3,r4,r6 blink tr0,r63 /* Rearranged to make cut2 safe */ .balign 8 L4_7: /* 4..7 byte memcpy cntd. */ stlo.l r2, 0, r0 or r6, r7, r6 sthi.l r5, -1, r6 stlo.l r5, -4, r6 blink tr1,r63 .balign 8 L1: /* 0 byte memcpy */ nop blink tr1,r63 nop nop nop nop L2_3: /* 2 or 3 byte memcpy cntd. */ st.b r5,-1,r6 blink tr1,r63 /* 1 byte memcpy */ ld.b r3,0,r0 st.b r2,0,r0 blink tr1,r63 L8_15: /* 8..15 byte memcpy cntd. */ stlo.q r2, 0, r0 or r6, r7, r6 sthi.q r5, -1, r6 stlo.q r5, -8, r6 blink tr1,r63 /* 2 or 3 byte memcpy */ ld.b r3,0,r0 nop ! ld.b r2,0,r63 ! TAKum03020 ld.b r3,1,r1 st.b r2,0,r0 pta/l L2_3,tr0 ld.b r6,-1,r6 st.b r2,1,r1 blink tr0, r63 /* 4 .. 7 byte memcpy */ LDUAL (r3, 0, r0, r1) pta L4_7, tr0 ldlo.l r6, -4, r7 or r0, r1, r0 sthi.l r2, 3, r0 ldhi.l r6, -1, r6 blink tr0, r63 /* 8 .. 15 byte memcpy */ LDUAQ (r3, 0, r0, r1) pta L8_15, tr0 ldlo.q r6, -8, r7 or r0, r1, r0 sthi.q r2, 7, r0 ldhi.q r6, -1, r6 blink tr0, r63 /* 16 .. 24 byte memcpy */ LDUAQ (r3, 0, r0, r1) LDUAQ (r3, 8, r8, r9) or r0, r1, r0 sthi.q r2, 7, r0 or r8, r9, r8 sthi.q r2, 15, r8 ldlo.q r6, -8, r7 ldhi.q r6, -1, r6 stlo.q r2, 8, r8 stlo.q r2, 0, r0 or r6, r7, r6 sthi.q r5, -1, r6 stlo.q r5, -8, r6 blink tr1,r63 Large: ! ld.b r2, 0, r63 ! TAKum03020 pta/l Loop_ua, tr1 ori r3, -8, r7 sub r2, r7, r22 sub r3, r2, r6 add r2, r4, r5 ldlo.q r3, 0, r0 addi r5, -16, r5 movi 64+8, r27 ! could subtract r7 from that. stlo.q r2, 0, r0 sthi.q r2, 7, r0 ldx.q r22, r6, r0 bgtu/l r27, r4, tr1 addi r5, -48, r27 pta/l Loop_line, tr0 addi r6, 64, r36 addi r6, -24, r19 addi r6, -16, r20 addi r6, -8, r21 Loop_line: ! ldx.q r22, r36, r63 ! TAKum03020 alloco r22, 32 synco addi r22, 32, r22 ldx.q r22, r19, r23 sthi.q r22, -25, r0 ldx.q r22, r20, r24 ldx.q r22, r21, r25 stlo.q r22, -32, r0 ldx.q r22, r6, r0 sthi.q r22, -17, r23 sthi.q r22, -9, r24 sthi.q r22, -1, r25 stlo.q r22, -24, r23 stlo.q r22, -16, r24 stlo.q r22, -8, r25 bgeu r27, r22, tr0 Loop_ua: addi r22, 8, r22 sthi.q r22, -1, r0 stlo.q r22, -8, r0 ldx.q r22, r6, r0 bgtu/l r5, r22, tr1 add r3, r4, r7 ldlo.q r7, -8, r1 sthi.q r22, 7, r0 ldhi.q r7, -1, r7 ptabs r18,tr1 stlo.q r22, 0, r0 or r1, r7, r1 sthi.q r5, 15, r1 stlo.q r5, 8, r1 blink tr1, r63 copy_user_memcpy_end: nop