Add qemu 2.4.0

[kvmfornfv.git] / qemu / roms / qemu-palcode / strlen.S

diff --git a/qemu/roms/qemu-palcode/strlen.S b/qemu/roms/qemu-palcode/strlen.S
new file mode 100644 (file)
index 0000000..5a77d72
--- /dev/null
+++ b/qemu/roms/qemu-palcode/strlen.S
@@ -0,0 +1,59 @@
+/*
+ * strlen.S (c) 1995 David Mosberger (davidm@cs.arizona.edu)
+ *
+ * Finds length of a 0-terminated string.  Optimized for the
+ * Alpha architecture:
+ *
+ *     - memory accessed as aligned quadwords only
+ *     - uses bcmpge to compare 8 bytes in parallel
+ *     - does binary search to find 0 byte in last
+ *       quadword (HAKMEM needed 12 instructions to
+ *       do this instead of the 9 instructions that
+ *       binary search needs).
+ */
+
+       .set noreorder
+       .set noat
+
+       .align 3
+
+       .globl  strlen
+       .ent    strlen
+strlen:
+       .frame  $sp, 0, $26, 0
+       .prologue 0
+
+       ldq_u   $1, 0($16)      # load first quadword ($16  may be misaligned)
+       lda     $2, -1($31)
+       insqh   $2, $16, $2
+       andnot  $16, 7, $0
+       or      $2, $1, $1
+       cmpbge  $31, $1, $2     # $2  <- bitmask: bit i == 1 <==> i-th byte == 0
+       bne     $2, found
+
+loop:  ldq     $1, 8($0)
+       addq    $0, 8, $0       # addr += 8
+       nop                     # helps dual issue last two insns
+       cmpbge  $31, $1, $2
+       beq     $2, loop
+
+found: blbs    $2, done        # make aligned case fast
+       negq    $2, $3
+       and     $2, $3, $2
+
+       and     $2, 0x0f, $1
+       addq    $0, 4, $3
+       cmoveq  $1, $3, $0
+
+       and     $2, 0x33, $1
+       addq    $0, 2, $3
+       cmoveq  $1, $3, $0
+
+       and     $2, 0x55, $1
+       addq    $0, 1, $3
+       cmoveq  $1, $3, $0
+
+done:  subq    $0, $16, $0
+       ret     $31, ($26)
+
+       .end    strlen