1 files changed, 87 insertions, 0 deletions

diff --git a/arch/alpha/lib/strrchr.S b/arch/alpha/lib/strrchr.S
new file mode 100644
index 000000000000..82cfd0ac907b
--- /dev/null
+++ b/arch/alpha/lib/strrchr.S
@@ -0,0 +1,87 @@
+/*
+ * arch/alpha/lib/strrchr.S
+ * Contributed by Richard Henderson (rth@tamu.edu)
+ *
+ * Return the address of the last occurrence of a given character
+ * within a null-terminated string, or null if it is not found.
+ */
+
+#include <asm/regdef.h>
+
+        .set noreorder
+        .set noat
+
+        .align 3
+        .ent strrchr
+        .globl strrchr
+strrchr:
+        .frame sp, 0, ra
+        .prologue 0
+
+        zapnot  a1, 1, a1       # e0    : zero extend our test character
+        mov     zero, t6        # .. e1 : t6 is last match aligned addr
+        sll     a1, 8, t5       # e0    : replicate our test character
+        mov     zero, t8        # .. e1 : t8 is last match byte compare mask
+        or      t5, a1, a1      # e0    :
+        ldq_u   t0, 0(a0)       # .. e1 : load first quadword
+        sll     a1, 16, t5      # e0    :
+        andnot  a0, 7, v0       # .. e1 : align source addr
+        or      t5, a1, a1      # e0    :
+        lda     t4, -1          # .. e1 : build garbage mask
+        sll     a1, 32, t5      # e0    :
+        cmpbge  zero, t0, t1    # .. e1 : bits set iff byte == zero
+        mskqh   t4, a0, t4      # e0    :
+        or      t5, a1, a1      # .. e1 : character replication complete
+        xor     t0, a1, t2      # e0    : make bytes == c zero
+        cmpbge  zero, t4, t4    # .. e1 : bits set iff byte is garbage
+        cmpbge  zero, t2, t3    # e0    : bits set iff byte == c
+        andnot  t1, t4, t1      # .. e1 : clear garbage from null test
+        andnot  t3, t4, t3      # e0    : clear garbage from char test
+        bne     t1, $eos        # .. e1 : did we already hit the terminator?
+
+        /* Character search main loop */
+$loop:
+        ldq     t0, 8(v0)       # e0    : load next quadword
+        cmovne  t3, v0, t6      # .. e1 : save previous comparisons match
+        cmovne  t3, t3, t8      # e0    :
+        addq    v0, 8, v0       # .. e1 :
+        xor     t0, a1, t2      # e0    :
+        cmpbge  zero, t0, t1    # .. e1 : bits set iff byte == zero
+        cmpbge  zero, t2, t3    # e0    : bits set iff byte == c
+        beq     t1, $loop       # .. e1 : if we havnt seen a null, loop
+
+        /* Mask out character matches after terminator */
+$eos:
+        negq    t1, t4          # e0    : isolate first null byte match
+        and     t1, t4, t4      # e1    :
+        subq    t4, 1, t5       # e0    : build a mask of the bytes upto...
+        or      t4, t5, t4      # e1    : ... and including the null
+
+        and     t3, t4, t3      # e0    : mask out char matches after null
+        cmovne  t3, t3, t8      # .. e1 : save it, if match found
+        cmovne  t3, v0, t6      # e0    :
+
+        /* Locate the address of the last matched character */
+
+        /* Retain the early exit for the ev4 -- the ev5 mispredict penalty
+           is 5 cycles -- the same as just falling through.  */
+        beq     t8, $retnull    # .. e1 :
+
+        and     t8, 0xf0, t2    # e0    : binary search for the high bit set
+        cmovne  t2, t2, t8      # .. e1 (zdb)
+        cmovne  t2, 4, t2       # e0    :
+        and     t8, 0xcc, t1    # .. e1 :
+        cmovne  t1, t1, t8      # e0    :
+        cmovne  t1, 2, t1       # .. e1 :
+        and     t8, 0xaa, t0    # e0    :
+        cmovne  t0, 1, t0       # .. e1 (zdb)
+        addq    t2, t1, t1      # e0    :
+        addq    t6, t0, v0      # .. e1 : add our aligned base ptr to the mix
+        addq    v0, t1, v0      # e0    :
+        ret                     # .. e1 :
+
+$retnull:
+        mov     zero, v0        # e0    :
+        ret                     # .. e1 :
+
+        .end strrchr