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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/alpha/lib/ev6-memcpy.S
downloadlinux-stericsson-2.6.12-rc2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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+/*
+ * arch/alpha/lib/ev6-memcpy.S
+ * 21264 version by Rick Gorton <rick.gorton@alpha-processor.com>
+ *
+ * Reasonably optimized memcpy() routine for the Alpha 21264
+ *
+ * - memory accessed as aligned quadwords only
+ * - uses bcmpge to compare 8 bytes in parallel
+ *
+ * Much of the information about 21264 scheduling/coding comes from:
+ * Compiler Writer's Guide for the Alpha 21264
+ * abbreviated as 'CWG' in other comments here
+ * ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html
+ * Scheduling notation:
+ * E - either cluster
+ * U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1
+ * L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1
+ *
+ * Temp usage notes:
+ * $1,$2, - scratch
+ */
+
+ .set noreorder
+ .set noat
+
+ .align 4
+ .globl memcpy
+ .ent memcpy
+memcpy:
+ .frame $30,0,$26,0
+ .prologue 0
+
+ mov $16, $0 # E : copy dest to return
+ ble $18, $nomoredata # U : done with the copy?
+ xor $16, $17, $1 # E : are source and dest alignments the same?
+ and $1, 7, $1 # E : are they the same mod 8?
+
+ bne $1, $misaligned # U : Nope - gotta do this the slow way
+ /* source and dest are same mod 8 address */
+ and $16, 7, $1 # E : Are both 0mod8?
+ beq $1, $both_0mod8 # U : Yes
+ nop # E :
+
+ /*
+ * source and dest are same misalignment. move a byte at a time
+ * until a 0mod8 alignment for both is reached.
+ * At least one byte more to move
+ */
+
+$head_align:
+ ldbu $1, 0($17) # L : grab a byte
+ subq $18, 1, $18 # E : count--
+ addq $17, 1, $17 # E : src++
+ stb $1, 0($16) # L :
+ addq $16, 1, $16 # E : dest++
+ and $16, 7, $1 # E : Are we at 0mod8 yet?
+ ble $18, $nomoredata # U : done with the copy?
+ bne $1, $head_align # U :
+
+$both_0mod8:
+ cmple $18, 127, $1 # E : Can we unroll the loop?
+ bne $1, $no_unroll # U :
+ and $16, 63, $1 # E : get mod64 alignment
+ beq $1, $do_unroll # U : no single quads to fiddle
+
+$single_head_quad:
+ ldq $1, 0($17) # L : get 8 bytes
+ subq $18, 8, $18 # E : count -= 8
+ addq $17, 8, $17 # E : src += 8
+ nop # E :
+
+ stq $1, 0($16) # L : store
+ addq $16, 8, $16 # E : dest += 8
+ and $16, 63, $1 # E : get mod64 alignment
+ bne $1, $single_head_quad # U : still not fully aligned
+
+$do_unroll:
+ addq $16, 64, $7 # E : Initial (+1 trip) wh64 address
+ cmple $18, 127, $1 # E : Can we go through the unrolled loop?
+ bne $1, $tail_quads # U : Nope
+ nop # E :
+
+$unroll_body:
+ wh64 ($7) # L1 : memory subsystem hint: 64 bytes at
+ # ($7) are about to be over-written
+ ldq $6, 0($17) # L0 : bytes 0..7
+ nop # E :
+ nop # E :
+
+ ldq $4, 8($17) # L : bytes 8..15
+ ldq $5, 16($17) # L : bytes 16..23
+ addq $7, 64, $7 # E : Update next wh64 address
+ nop # E :
+
+ ldq $3, 24($17) # L : bytes 24..31
+ addq $16, 64, $1 # E : fallback value for wh64
+ nop # E :
+ nop # E :
+
+ addq $17, 32, $17 # E : src += 32 bytes
+ stq $6, 0($16) # L : bytes 0..7
+ nop # E :
+ nop # E :
+
+ stq $4, 8($16) # L : bytes 8..15
+ stq $5, 16($16) # L : bytes 16..23
+ subq $18, 192, $2 # E : At least two more trips to go?
+ nop # E :
+
+ stq $3, 24($16) # L : bytes 24..31
+ addq $16, 32, $16 # E : dest += 32 bytes
+ nop # E :
+ nop # E :
+
+ ldq $6, 0($17) # L : bytes 0..7
+ ldq $4, 8($17) # L : bytes 8..15
+ cmovlt $2, $1, $7 # E : Latency 2, extra map slot - Use
+ # fallback wh64 address if < 2 more trips
+ nop # E :
+
+ ldq $5, 16($17) # L : bytes 16..23
+ ldq $3, 24($17) # L : bytes 24..31
+ addq $16, 32, $16 # E : dest += 32
+ subq $18, 64, $18 # E : count -= 64
+
+ addq $17, 32, $17 # E : src += 32
+ stq $6, -32($16) # L : bytes 0..7
+ stq $4, -24($16) # L : bytes 8..15
+ cmple $18, 63, $1 # E : At least one more trip?
+
+ stq $5, -16($16) # L : bytes 16..23
+ stq $3, -8($16) # L : bytes 24..31
+ nop # E :
+ beq $1, $unroll_body
+
+$tail_quads:
+$no_unroll:
+ .align 4
+ subq $18, 8, $18 # E : At least a quad left?
+ blt $18, $less_than_8 # U : Nope
+ nop # E :
+ nop # E :
+
+$move_a_quad:
+ ldq $1, 0($17) # L : fetch 8
+ subq $18, 8, $18 # E : count -= 8
+ addq $17, 8, $17 # E : src += 8
+ nop # E :
+
+ stq $1, 0($16) # L : store 8
+ addq $16, 8, $16 # E : dest += 8
+ bge $18, $move_a_quad # U :
+ nop # E :
+
+$less_than_8:
+ .align 4
+ addq $18, 8, $18 # E : add back for trailing bytes
+ ble $18, $nomoredata # U : All-done
+ nop # E :
+ nop # E :
+
+ /* Trailing bytes */
+$tail_bytes:
+ subq $18, 1, $18 # E : count--
+ ldbu $1, 0($17) # L : fetch a byte
+ addq $17, 1, $17 # E : src++
+ nop # E :
+
+ stb $1, 0($16) # L : store a byte
+ addq $16, 1, $16 # E : dest++
+ bgt $18, $tail_bytes # U : more to be done?
+ nop # E :
+
+ /* branching to exit takes 3 extra cycles, so replicate exit here */
+ ret $31, ($26), 1 # L0 :
+ nop # E :
+ nop # E :
+ nop # E :
+
+$misaligned:
+ mov $0, $4 # E : dest temp
+ and $0, 7, $1 # E : dest alignment mod8
+ beq $1, $dest_0mod8 # U : life doesnt totally suck
+ nop
+
+$aligndest:
+ ble $18, $nomoredata # U :
+ ldbu $1, 0($17) # L : fetch a byte
+ subq $18, 1, $18 # E : count--
+ addq $17, 1, $17 # E : src++
+
+ stb $1, 0($4) # L : store it
+ addq $4, 1, $4 # E : dest++
+ and $4, 7, $1 # E : dest 0mod8 yet?
+ bne $1, $aligndest # U : go until we are aligned.
+
+ /* Source has unknown alignment, but dest is known to be 0mod8 */
+$dest_0mod8:
+ subq $18, 8, $18 # E : At least a quad left?
+ blt $18, $misalign_tail # U : Nope
+ ldq_u $3, 0($17) # L : seed (rotating load) of 8 bytes
+ nop # E :
+
+$mis_quad:
+ ldq_u $16, 8($17) # L : Fetch next 8
+ extql $3, $17, $3 # U : masking
+ extqh $16, $17, $1 # U : masking
+ bis $3, $1, $1 # E : merged bytes to store
+
+ subq $18, 8, $18 # E : count -= 8
+ addq $17, 8, $17 # E : src += 8
+ stq $1, 0($4) # L : store 8 (aligned)
+ mov $16, $3 # E : "rotate" source data
+
+ addq $4, 8, $4 # E : dest += 8
+ bge $18, $mis_quad # U : More quads to move
+ nop
+ nop
+
+$misalign_tail:
+ addq $18, 8, $18 # E : account for tail stuff
+ ble $18, $nomoredata # U :
+ nop
+ nop
+
+$misalign_byte:
+ ldbu $1, 0($17) # L : fetch 1
+ subq $18, 1, $18 # E : count--
+ addq $17, 1, $17 # E : src++
+ nop # E :
+
+ stb $1, 0($4) # L : store
+ addq $4, 1, $4 # E : dest++
+ bgt $18, $misalign_byte # U : more to go?
+ nop
+
+
+$nomoredata:
+ ret $31, ($26), 1 # L0 :
+ nop # E :
+ nop # E :
+ nop # E :
+
+ .end memcpy
+
+/* For backwards module compatibility. */
+__memcpy = memcpy
+.globl __memcpy