Move CLZ emulation to common code

Move the CLZ instruction emulation C code to the common directory, so it
can be reused for all CPU cores missing a CLZ instruction (e.g. CortexM0).

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>

BRANCH=none
BUG=none
TEST=run EC console on STM32F072B Discovery board with Cortex-M0 core,
and pass all available unit-tests on target.

Change-Id: Ief56cac7430fcb0fbced8a8925250c89cbd0bcfc
Reviewed-on: https://chromium-review.googlesource.com/188981
Reviewed-by: Alec Berg <alecaberg@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Commit-Queue: Vincent Palatin <vpalatin@chromium.org>
Tested-by: Vincent Palatin <vpalatin@chromium.org>

2 files changed, 5 insertions, 39 deletions

diff --git a/core/nds32/config_core.h b/core/nds32/config_core.h
index d7a25d27da..750d47b016 100644
--- a/core/nds32/config_core.h
+++ b/core/nds32/config_core.h
@@ -10,6 +10,11 @@
 #define BFD_ARCH nds32
 #define BFD_FORMAT "elf32-nds32le"
 
+/*
+ * The Andestar v3m architecture has no CLZ instruction (contrary to v3),
+ * so let's use the software implementation.
+ */
+#define CONFIG_SOFTWARE_CLZ
 
 /*
  * Force the compiler to use a proper relocation when accessing an external
diff --git a/core/nds32/cpu.c b/core/nds32/cpu.c
index e4dc5db94c..545e930eca 100644
--- a/core/nds32/cpu.c
+++ b/core/nds32/cpu.c
@@ -11,42 +11,3 @@ void cpu_init(void)
 {
 	/* DLM initialization is done in init.S */
 }
-
-/**
- * Count leading zeros
- *
- * @param x non null integer.
- * @return the number of leading 0-bits in x,
- * starting at the most significant bit position.
- *
- * The Andestar v3m architecture has no CLZ instruction (contrary to v3),
- * so let's use the software implementation.
- */
-int __clzsi2(int x)
-{
-	int r = 0;
-
-	if (!x)
-		return 32;
-	if (!(x & 0xffff0000u)) {
-		x <<= 16;
-		r += 16;
-	}
-	if (!(x & 0xff000000u)) {
-		x <<= 8;
-		r += 8;
-	}
-	if (!(x & 0xf0000000u)) {
-		x <<= 4;
-		r += 4;
-	}
-	if (!(x & 0xc0000000u)) {
-		x <<= 2;
-		r += 2;
-	}
-	if (!(x & 0x80000000u)) {
-		x <<= 1;
-		r += 1;
-	}
-	return r;
-}