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[PATCH 2/2 roland/arm-memchr] ARM: Make armv6t2 memchr implementation usable without Thumb.
ports/ChangeLog.arm
* sysdeps/arm/armv6t2/memchr.S [NO_THUMB]:
Use .arm rather than .thumb, .thumb_func. Avoid cbz/cnbz instructions.
--- a/ports/sysdeps/arm/armv6t2/memchr.S
+++ b/ports/sysdeps/arm/armv6t2/memchr.S
@@ -42,10 +42,12 @@
.syntax unified
.text
+#ifdef NO_THUMB
+ .arm
+#else
.thumb
-
-@ ---------------------------------------------------------------------------
.thumb_func
+#endif
.global memchr
.type memchr,%function
ENTRY(memchr)
@@ -89,14 +91,22 @@ ENTRY(memchr)
15:
ldrd r4,r5, [r0],#8
+#ifndef NO_THUMB
subs r6, r6, #8
+#endif
eor r4,r4, r1 @ Get it so that r4,r5 have 00's where the bytes match the target
eor r5,r5, r1
uadd8 r4, r4, r7 @ Parallel add 0xff - sets the GE bits for anything that wasn't 0
sel r4, r3, r7 @ bytes are 00 for none-00 bytes, or ff for 00 bytes - NOTE INVERSION
uadd8 r5, r5, r7 @ Parallel add 0xff - sets the GE bits for anything that wasn't 0
sel r5, r4, r7 @ chained....bytes are 00 for none-00 bytes, or ff for 00 bytes - NOTE INVERSION
+#ifndef NO_THUMB
cbnz r5, 60f
+#else
+ cmp r5, #0
+ bne 60f
+ subs r6, r6, #8
+#endif
bne 15b @ (Flags from the subs above) If not run out of bytes then go around again
pop {r4,r5,r6,r7}
@@ -110,13 +120,24 @@ ENTRY(memchr)
and r2,r2,#7 @ Leave the count remaining as the number after the double words have been done
20:
+#ifndef NO_THUMB
cbz r2, 40f @ 0 length or hit the end already then not found
+#else
+ cmp r2, #0
+ beq 40f
+#endif
21: @ Post aligned section, or just a short call
ldrb r3,[r0],#1
+#ifndef NO_THUMB
subs r2,r2,#1
eor r3,r3,r1 @ r3 = 0 if match - doesn't break flags from sub
cbz r3, 50f
+#else
+ eors r3, r3, r1
+ beq 50f
+ subs r2, r2, #1
+#endif
bne 21b @ on r2 flags
40: