* libc/machine/arm/strcmp.S: New File.

	* libc/machine/arm/strcmp.c: Deleted.
	* libc/machine/arm/Makefile.am: Replaces strcmp.c with strcmp.S
	* libc/machine/arm/Makefile.in: Regenerated.
	* testsuite/newlib.string/strcmp-1.c: New file.

1 files changed, 777 insertions, 0 deletions

diff --git a/newlib/libc/machine/arm/strcmp.S b/newlib/libc/machine/arm/strcmp.S
new file mode 100644
index 000000000..6298bc98d
--- /dev/null
+++ b/newlib/libc/machine/arm/strcmp.S
@@ -0,0 +1,777 @@
+/*
+ * Copyright (c) 2012 ARM Ltd
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the company may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY ARM LTD ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL ARM LTD BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "arm_asm.h"
+
+#ifdef __ARMEB__
+#define S2LOMEM lsl
+#define S2LOMEMEQ lsleq
+#define S2HIMEM lsr
+#define MSB 0x000000ff
+#define LSB 0xff000000
+#define BYTE0_OFFSET 24
+#define BYTE1_OFFSET 16
+#define BYTE2_OFFSET 8
+#define BYTE3_OFFSET 0
+#else /* not  __ARMEB__ */
+#define S2LOMEM lsr
+#define S2LOMEMEQ lsreq
+#define S2HIMEM lsl
+#define BYTE0_OFFSET 0
+#define BYTE1_OFFSET 8
+#define BYTE2_OFFSET 16
+#define BYTE3_OFFSET 24
+#define MSB 0xff000000
+#define LSB 0x000000ff
+#endif /* not  __ARMEB__ */
+
+.syntax         unified
+
+#if defined (__thumb__)
+        .thumb
+        .thumb_func
+#endif
+        .global strcmp
+        .type   strcmp, %function
+strcmp:
+
+#if (defined (__thumb__) && !defined (__thumb2__))
+1:
+        ldrb    r2, [r0]
+        ldrb    r3, [r1]
+        adds    r0, r0, #1
+        adds    r1, r1, #1
+        cmp     r2, #0
+        beq     2f
+        cmp     r2, r3
+        beq     1b
+2:
+        subs    r0, r2, r3
+        bx      lr
+#elif (defined (__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED))
+1:
+        ldrb    r2, [r0], #1
+        ldrb    r3, [r1], #1
+        cmp     r2, #1
+        it      cs
+        cmpcs   r2, r3
+        beq     1b
+        subs    r0, r2, r3
+        RETURN
+
+
+#elif (defined (_ISA_THUMB_2) || defined (_ISA_ARM_6))
+      /* Use LDRD whenever possible.  */
+
+/* The main thing to look out for when comparing large blocks is that
+   the loads do not cross a page boundary when loading past the index
+   of the byte with the first difference or the first string-terminator.
+
+   For example, if the strings are identical and the string-terminator
+   is at index k, byte by byte comparison will not load beyond address
+   s1+k and s2+k; word by word comparison may load up to 3 bytes beyond
+   k; double word - up to 7 bytes.  If the load of these bytes crosses
+   a page boundary, it might cause a memory fault (if the page is not mapped)
+   that would not have happened in byte by byte comparison.
+
+   If an address is (double) word aligned, then a load of a (double) word
+   from that address will not cross a page boundary.
+   Therefore, the algorithm below considers word and double-word alignment
+   of strings separately.  */
+
+/* High-level description of the algorithm.
+
+   * The fast path: if both strings are double-word aligned,
+     use LDRD to load two words from each string in every loop iteration.
+   * If the strings have the same offset from a word boundary,
+     use LDRB to load and compare byte by byte until
+     the first string is aligned to a word boundary (at most 3 bytes).
+     This is optimized for quick return on short unaligned strings.
+   * If the strings have the same offset from a double-word boundary,
+     use LDRD to load two words from each string in every loop iteration, as in the fast path.
+   * If the strings do not have the same offset from a double-word boundary,
+     load a word from the second string before the loop to initialize the queue.
+     Use LDRD to load two words from every string in every loop iteration.
+     Inside the loop, load the second word from the second string only after comparing
+     the first word, using the queued value, to guarantee safety across page boundaries.
+   * If the strings do not have the same offset from a word boundary,
+     use LDR and a shift queue. Order of loads and comparisons matters,
+     similarly to the previous case.
+
+   * Use UADD8 and SEL to compare words, and use REV and CLZ to compute the return value.
+   * The only difference between ARM and Thumb modes is the use of CBZ instruction.
+   * The only difference between big and little endian is the use of REV in little endian
+     to compute the return value, instead of MOV.
+   * No preload. [TODO.]
+*/
+
+        .macro m_cbz reg label
+#ifdef __thumb2__
+        cbz     \reg, \label
+#else   /* not defined __thumb2__ */
+        cmp     \reg, #0
+        beq     \label
+#endif /* not defined __thumb2__ */
+        .endm /* m_cbz */
+
+        .macro m_cbnz reg label
+#ifdef __thumb2__
+        cbnz    \reg, \label
+#else   /* not defined __thumb2__ */
+        cmp     \reg, #0
+        bne     \label
+#endif /* not defined __thumb2__ */
+        .endm /* m_cbnz */
+
+        .macro  init
+        /* Macro to save temporary registers and prepare magic values.  */
+        subs    sp, sp, #16
+        strd    r4, r5, [sp, #8]
+        strd    r6, r7, [sp]
+        mvn     r6, #0  /* all F */
+        mov     r7, #0  /* all 0 */
+        .endm   /* init */
+
+        .macro  magic_compare_and_branch w1 w2 label
+        /* Macro to compare registers w1 and w2 and conditionally branch to label.  */
+        cmp     \w1, \w2        /* Are w1 and w2 the same?  */
+        magic_find_zero_bytes \w1
+        it      eq
+        cmpeq   ip, #0          /* Is there a zero byte in w1?  */
+        bne     \label
+        .endm /* magic_compare_and_branch */
+
+        .macro  magic_find_zero_bytes w1
+        /* Macro to find all-zero bytes in w1, result is in ip.  */
+#if (defined (__ARM_FEATURE_DSP))
+        uadd8   ip, \w1, r6
+        sel     ip, r7, r6
+#else /* not defined (__ARM_FEATURE_DSP) */
+        /* __ARM_FEATURE_DSP is not defined for some Cortex-M processors.
+        Coincidently, these processors only have Thumb-2 mode, where we can use the
+        the (large) magic constant available directly as an immediate in instructions.
+        Note that we cannot use the magic constant in ARM mode, where we need
+        to create the constant in a register.  */
+        sub     ip, \w1, #0x01010101
+        bic     ip, ip, \w1
+        and     ip, ip, #0x80808080
+#endif /* not defined (__ARM_FEATURE_DSP) */
+        .endm /* magic_find_zero_bytes */
+
+        .macro  setup_return w1 w2
+#ifdef __ARMEB__
+        mov     r1, \w1
+        mov     r2, \w2
+#else /* not  __ARMEB__ */
+        rev     r1, \w1
+        rev     r2, \w2
+#endif /* not  __ARMEB__ */
+        .endm /* setup_return */
+
+        /*
+        optpld r0, #0
+        optpld r1, #0
+        */
+
+        /* Are both strings double-word aligned?  */
+        orr     ip, r0, r1
+        tst     ip, #7
+        bne     do_align
+
+        /* Fast path.  */
+        init
+
+doubleword_aligned:
+
+        /* Get here when the strings to compare are double-word aligned.  */
+        /* Compare two words in every iteration.  */
+        .p2align        2
+2:
+        /*
+        optpld r0, #16
+        optpld r1, #16
+        */
+
+        /* Load the next double-word from each string.  */
+        ldrd    r2, r3, [r0], #8
+        ldrd    r4, r5, [r1], #8
+
+        magic_compare_and_branch w1=r2, w2=r4, label=return_24
+        magic_compare_and_branch w1=r3, w2=r5, label=return_35
+        b       2b
+
+do_align:
+        /* Is the first string word-aligned?  */
+        ands    ip, r0, #3
+        beq     word_aligned_r0
+
+        /* Fast compare byte by byte until the first string is word-aligned.  */
+        /* The offset of r0 from a word boundary is in ip. Thus, the number of bytes
+        to read until the next word boudnary is 4-ip.  */
+        bic     r0, r0, #3
+        ldr     r2, [r0], #4
+        lsls    ip, ip, #31
+        beq     byte2
+        bcs     byte3
+
+byte1:
+        ldrb    ip, [r1], #1
+        uxtb    r3, r2, ror #BYTE1_OFFSET
+        subs    ip, r3, ip
+        bne     fast_return
+        m_cbz   reg=r3, label=fast_return
+
+byte2:
+        ldrb    ip, [r1], #1
+        uxtb    r3, r2, ror #BYTE2_OFFSET
+        subs    ip, r3, ip
+        bne     fast_return
+        m_cbz   reg=r3, label=fast_return
+
+byte3:
+        ldrb    ip, [r1], #1
+        uxtb    r3, r2, ror #BYTE3_OFFSET
+        subs    ip, r3, ip
+        bne     fast_return
+        m_cbnz  reg=r3, label=word_aligned_r0
+
+fast_return:
+        mov     r0, ip
+        bx      lr
+
+word_aligned_r0:
+        init
+        /* The first string is word-aligned.  */
+        /* Is the second string word-aligned?  */
+        ands    ip, r1, #3
+        bne     strcmp_unaligned
+
+word_aligned:
+        /* The strings are word-aligned. */
+        /* Is the first string double-word aligned?  */
+        tst     r0, #4
+        beq     doubleword_aligned_r0
+
+        /* If r0 is not double-word aligned yet, align it by loading
+        and comparing the next word from each string.  */
+        ldr     r2, [r0], #4
+        ldr     r4, [r1], #4
+        magic_compare_and_branch w1=r2 w2=r4 label=return_24
+
+doubleword_aligned_r0:
+        /* Get here when r0 is double-word aligned.  */
+        /* Is r1 doubleword_aligned?  */
+        tst     r1, #4
+        beq     doubleword_aligned
+
+        /* Get here when the strings to compare are word-aligned,
+        r0 is double-word aligned, but r1 is not double-word aligned.  */
+
+        /* Initialize the queue.  */
+        ldr     r5, [r1], #4
+
+        /* Compare two words in every iteration.  */
+        .p2align        2
+3:
+        /*
+        optpld r0, #16
+        optpld r1, #16
+        */
+
+        /* Load the next double-word from each string and compare.  */
+        ldrd    r2, r3, [r0], #8
+        magic_compare_and_branch w1=r2 w2=r5 label=return_25
+        ldrd    r4, r5, [r1], #8
+        magic_compare_and_branch w1=r3 w2=r4 label=return_34
+        b       3b
+
+        .macro miscmp_word offsetlo offsethi
+        /* Macro to compare misaligned strings.  */
+        /* r0, r1 are word-aligned, and at least one of the strings
+        is not double-word aligned.  */
+        /* Compare one word in every loop iteration.  */
+        /* OFFSETLO is the original bit-offset of r1 from a word-boundary,
+        OFFSETHI is 32 - OFFSETLO (i.e., offset from the next word).  */
+
+        /* Initialize the shift queue.  */
+        ldr     r5, [r1], #4
+
+        /* Compare one word from each string in every loop iteration.  */
+        .p2align        2
+7:
+        ldr     r3, [r0], #4
+        S2LOMEM r5, r5, #\offsetlo
+        magic_find_zero_bytes w1=r3
+        cmp     r7, ip, S2HIMEM #\offsetlo
+        and     r2, r3, r6, S2LOMEM #\offsetlo
+        it      eq
+        cmpeq   r2, r5
+        bne     return_25
+        ldr     r5, [r1], #4
+        cmp     ip, #0
+        eor	r3, r2, r3
+        S2HIMEM r2, r5, #\offsethi
+        it      eq
+        cmpeq   r3, r2
+        bne     return_32
+        b       7b
+        .endm /* miscmp_word */
+
+strcmp_unaligned:
+        /* r0 is word-aligned, r1 is at offset ip from a word.  */
+        /* Align r1 to the (previous) word-boundary.  */
+        bic     r1, r1, #3
+
+        /* Unaligned comparison word by word using LDRs. */
+        cmp     ip, #2
+        beq     miscmp_word_16                    /* If ip == 2.  */
+        bge     miscmp_word_24                    /* If ip == 3.  */
+        miscmp_word offsetlo=8 offsethi=24        /* If ip == 1.  */
+miscmp_word_16:  miscmp_word offsetlo=16 offsethi=16
+miscmp_word_24:  miscmp_word offsetlo=24 offsethi=8
+
+
+return_32:
+        setup_return w1=r3, w2=r2
+        b       do_return
+return_34:
+        setup_return w1=r3, w2=r4
+        b       do_return
+return_25:
+        setup_return w1=r2, w2=r5
+        b       do_return
+return_35:
+        setup_return w1=r3, w2=r5
+        b       do_return
+return_24:
+        setup_return w1=r2, w2=r4
+
+do_return:
+
+#ifdef __ARMEB__
+        mov     r0, ip
+#else /* not  __ARMEB__ */
+        rev     r0, ip
+#endif /* not  __ARMEB__ */
+
+        /* Restore temporaries early, before computing the return value.  */
+        ldrd    r6, r7, [sp]
+        ldrd    r4, r5, [sp, #8]
+        adds    sp, sp, #16
+
+        /* There is a zero or a different byte between r1 and r2.  */
+        /* r0 contains a mask of all-zero bytes in r1.  */
+        /* Using r0 and not ip here because cbz requires low register.  */
+        m_cbz   reg=r0, label=compute_return_value
+        clz     r0, r0
+        /* r0 contains the number of bits on the left of the first all-zero byte in r1.  */
+        rsb     r0, r0, #24
+        /* Here, r0 contains the number of bits on the right of the first all-zero byte in r1.  */
+        lsr     r1, r1, r0
+        lsr     r2, r2, r0
+
+compute_return_value:
+        subs    r0, r1, r2
+        bx      lr
+
+
+#else   /* !(defined (_ISA_THUMB_2) || defined (_ISA_ARM_6)
+             defined (__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED) ||
+             (defined (__thumb__) && !defined (__thumb2__))) */
+
+        /* Use LDR whenever possible. */
+
+#ifdef __thumb2__
+#define magic1(REG) 0x01010101
+#define magic2(REG) 0x80808080
+#else
+#define magic1(REG) REG
+#define magic2(REG) REG, lsl #7
+#endif
+
+        optpld  r0
+        optpld  r1
+        eor     r2, r0, r1
+        tst     r2, #3
+        /* Strings not at same byte offset from a word boundary.  */
+        bne     strcmp_unaligned
+        ands    r2, r0, #3
+        bic     r0, r0, #3
+        bic     r1, r1, #3
+        ldr     ip, [r0], #4
+        it      eq
+        ldreq   r3, [r1], #4
+        beq     1f
+        /* Although s1 and s2 have identical initial alignment, they are
+        not currently word aligned.  Rather than comparing bytes,
+	make sure that any bytes fetched from before the addressed
+	bytes are forced to 0xff.  Then they will always compare
+	equal.  */
+        eor     r2, r2, #3
+        lsl     r2, r2, #3
+        mvn     r3, MSB
+        S2LOMEM        r2, r3, r2
+        ldr     r3, [r1], #4
+        orr     ip, ip, r2
+        orr     r3, r3, r2
+1:
+#ifndef __thumb2__
+              /* Load the 'magic' constant 0x01010101.  */
+        str     r4, [sp, #-4]!
+        mov     r4, #1
+        orr     r4, r4, r4, lsl #8
+        orr     r4, r4, r4, lsl #16
+#endif
+        .p2align        2
+4:
+        optpld  r0, #8
+        optpld  r1, #8
+        sub     r2, ip, magic1(r4)
+        cmp     ip, r3
+        itttt   eq
+        /* check for any zero bytes in first word */
+        biceq   r2, r2, ip
+        tsteq   r2, magic2(r4)
+        ldreq   ip, [r0], #4
+        ldreq   r3, [r1], #4
+        beq     4b
+2:
+        /* There's a zero or a different byte in the word */
+        S2HIMEM  r0, ip, #24
+        S2LOMEM  ip, ip, #8
+        cmp     r0, #1
+        it      cs
+        cmpcs   r0, r3, S2HIMEM #24
+        it      eq
+        S2LOMEMEQ r3, r3, #8
+        beq     2b
+        /* On a big-endian machine, r0 contains the desired byte in bits
+        0-7; on a little-endian machine they are in bits 24-31.  In
+        both cases the other bits in r0 are all zero.  For r3 the
+        interesting byte is at the other end of the word, but the
+        other bits are not necessarily zero.  We need a signed result
+        representing the differnece in the unsigned bytes, so for the
+        little-endian case we can't just shift the interesting bits
+        up.  */
+#ifdef __ARMEB__
+        sub     r0, r0, r3, lsr #24
+#else
+        and     r3, r3, #255
+#ifdef __thumb2__
+        /* No RSB instruction in Thumb2 */
+        lsr     r0, r0, #24
+        sub     r0, r0, r3
+#else
+        rsb     r0, r3, r0, lsr #24
+#endif
+#endif
+#ifndef __thumb2__
+        ldr     r4, [sp], #4
+#endif
+        RETURN
+
+
+strcmp_unaligned:
+
+#if 0
+        /* The assembly code below is based on the following alogrithm.  */
+#ifdef __ARMEB__
+#define RSHIFT <<
+#define LSHIFT >>
+#else
+#define RSHIFT >>
+#define LSHIFT <<
+#endif
+
+#define body(shift)							\
+  mask = 0xffffffffU RSHIFT shift;					\
+  w1 = *wp1++;								\
+  w2 = *wp2++;								\
+  do									\
+    {									\
+      t1 = w1 & mask;							\
+      if (__builtin_expect(t1 != w2 RSHIFT shift, 0))			\
+	{								\
+	  w2 RSHIFT= shift;						\
+	  break;							\
+	}								\
+      if (__builtin_expect(((w1 - b1) & ~w1) & (b1 << 7), 0))		\
+	{								\
+	  /* See comment in assembler below re syndrome on big-endian */\
+	  if ((((w1 - b1) & ~w1) & (b1 << 7)) & mask)			\
+	    w2 RSHIFT= shift;						\
+	  else								\
+	    {								\
+	      w2 = *wp2;						\
+	      t1 = w1 RSHIFT (32 - shift);				\
+	      w2 = (w2 LSHIFT (32 - shift)) RSHIFT (32 - shift);	\
+	    }								\
+	  break;							\
+	}								\
+      w2 = *wp2++;							\
+      t1 ^= w1;								\
+      if (__builtin_expect(t1 != w2 LSHIFT (32 - shift), 0))		\
+	{								\
+	  t1 = w1 >> (32 - shift);					\
+	  w2 = (w2 << (32 - shift)) RSHIFT (32 - shift);		\
+	  break;							\
+	}								\
+      w1 = *wp1++;							\
+    } while (1)
+
+  const unsigned* wp1;
+  const unsigned* wp2;
+  unsigned w1, w2;
+  unsigned mask;
+  unsigned shift;
+  unsigned b1 = 0x01010101;
+  char c1, c2;
+  unsigned t1;
+
+  while (((unsigned) s1) & 3)
+    {
+      c1 = *s1++;
+      c2 = *s2++;
+      if (c1 == 0 || c1 != c2)
+	return c1 - (int)c2;
+    }
+  wp1 = (unsigned*) (((unsigned)s1) & ~3);
+  wp2 = (unsigned*) (((unsigned)s2) & ~3);
+  t1 = ((unsigned) s2) & 3;
+  if (t1 == 1)
+    {
+      body(8);
+    }
+  else if (t1 == 2)
+    {
+      body(16);
+    }
+  else
+    {
+      body (24);
+    }
+
+  do
+    {
+#ifdef __ARMEB__
+      c1 = (char) t1 >> 24;
+      c2 = (char) w2 >> 24;
+#else /* not  __ARMEB__ */
+      c1 = (char) t1;
+      c2 = (char) w2;
+#endif /* not  __ARMEB__ */
+      t1 RSHIFT= 8;
+      w2 RSHIFT= 8;
+    } while (c1 != 0 && c1 == c2);
+  return c1 - c2;
+#endif /* 0 */
+
+
+        wp1 .req r0
+        wp2 .req r1
+        b1  .req r2
+        w1  .req r4
+        w2  .req r5
+        t1  .req ip
+        @ r3 is scratch
+
+        /* First of all, compare bytes until wp1(sp1) is word-aligned. */
+1:
+        tst     wp1, #3
+        beq     2f
+        ldrb    r2, [wp1], #1
+        ldrb    r3, [wp2], #1
+        cmp     r2, #1
+        it      cs
+        cmpcs   r2, r3
+        beq     1b
+        sub     r0, r2, r3
+        RETURN
+
+2:
+        str     r5, [sp, #-4]!
+        str     r4, [sp, #-4]!
+        //stmfd   sp!, {r4, r5}
+        mov     b1, #1
+        orr     b1, b1, b1, lsl #8
+        orr     b1, b1, b1, lsl #16
+
+        and     t1, wp2, #3
+        bic     wp2, wp2, #3
+        ldr     w1, [wp1], #4
+        ldr     w2, [wp2], #4
+        cmp     t1, #2
+        beq     2f
+        bhi     3f
+
+        /* Critical inner Loop: Block with 3 bytes initial overlap */
+        .p2align        2
+1:
+        bic     t1, w1, MSB
+        cmp     t1, w2, S2LOMEM #8
+        sub     r3, w1, b1
+        bic     r3, r3, w1
+        bne     4f
+        ands    r3, r3, b1, lsl #7
+        it      eq
+        ldreq   w2, [wp2], #4
+        bne     5f
+        eor     t1, t1, w1
+        cmp     t1, w2, S2HIMEM #24
+        bne     6f
+        ldr     w1, [wp1], #4
+        b       1b
+4:
+        S2LOMEM        w2, w2, #8
+        b       8f
+
+5:
+#ifdef __ARMEB__
+        /* The syndrome value may contain false ones if the string ends
+        with the bytes 0x01 0x00 */
+        tst     w1, #0xff000000
+        itt     ne
+        tstne   w1, #0x00ff0000
+        tstne   w1, #0x0000ff00
+        beq     7f
+#else
+        bics    r3, r3, #0xff000000
+        bne     7f
+#endif
+        ldrb    w2, [wp2]
+        S2LOMEM  t1, w1, #24
+#ifdef __ARMEB__
+        lsl     w2, w2, #24
+#endif
+        b       8f
+
+6:
+        S2LOMEM  t1, w1, #24
+        and     w2, w2, LSB
+        b       8f
+
+        /* Critical inner Loop: Block with 2 bytes initial overlap */
+        .p2align        2
+2:
+        S2HIMEM  t1, w1, #16
+        sub     r3, w1, b1
+        S2LOMEM  t1, t1, #16
+        bic     r3, r3, w1
+        cmp     t1, w2, S2LOMEM #16
+        bne     4f
+        ands    r3, r3, b1, lsl #7
+        it      eq
+        ldreq   w2, [wp2], #4
+        bne     5f
+        eor     t1, t1, w1
+        cmp     t1, w2, S2HIMEM #16
+        bne     6f
+        ldr     w1, [wp1], #4
+        b       2b
+
+5:
+#ifdef __ARMEB__
+        /* The syndrome value may contain false ones if the string ends
+        with the bytes 0x01 0x00 */
+        tst     w1, #0xff000000
+        it      ne
+        tstne   w1, #0x00ff0000
+        beq     7f
+#else
+        lsls    r3, r3, #16
+        bne     7f
+#endif
+        ldrh    w2, [wp2]
+        S2LOMEM  t1, w1, #16
+#ifdef __ARMEB__
+        lsl     w2, w2, #16
+#endif
+        b       8f
+
+6:
+        S2HIMEM  w2, w2, #16
+        S2LOMEM  t1, w1, #16
+4:
+        S2LOMEM  w2, w2, #16
+        b       8f
+
+        /* Critical inner Loop: Block with 1 byte initial overlap */
+        .p2align        2
+3:
+        and     t1, w1, LSB
+        cmp     t1, w2, S2LOMEM #24
+        sub     r3, w1, b1
+        bic     r3, r3, w1
+        bne     4f
+        ands    r3, r3, b1, lsl #7
+        it      eq
+        ldreq   w2, [wp2], #4
+        bne     5f
+        eor     t1, t1, w1
+        cmp     t1, w2, S2HIMEM #8
+        bne     6f
+        ldr     w1, [wp1], #4
+        b       3b
+4:
+        S2LOMEM  w2, w2, #24
+        b       8f
+5:
+        /* The syndrome value may contain false ones if the string ends
+        with the bytes 0x01 0x00 */
+        tst     w1, LSB
+        beq     7f
+        ldr     w2, [wp2], #4
+6:
+        S2LOMEM  t1, w1, #8
+        bic     w2, w2, MSB
+        b       8f
+7:
+        mov     r0, #0
+        //ldmfd   sp!, {r4, r5}
+        ldr     r4, [sp], #4
+        ldr     r5, [sp], #4
+        RETURN
+8:
+        and     r2, t1, LSB
+        and     r0, w2, LSB
+        cmp     r0, #1
+        it      cs
+        cmpcs   r0, r2
+        itt     eq
+        S2LOMEMEQ        t1, t1, #8
+        S2LOMEMEQ        w2, w2, #8
+        beq     8b
+        sub     r0, r2, r0
+        //ldmfd   sp!, {r4, r5}
+        ldr     r4, [sp], #4
+        ldr     r5, [sp], #4
+        RETURN
+
+#endif /* !(defined (_ISA_THUMB_2) || defined (_ISA_ARM_6)
+            defined (__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED) ||
+            (defined (__thumb__) && !defined (__thumb2__))) */