lib: Add __fls() (Find Last Set)

Implement __fls() as an alias for log2(), and remove the duplicate
definitions in commonlib/storage/sdhci.c.

Signed-off-by: Jianjun Wang <jianjun.wang@mediatek.com>
Change-Id: Ib458abfec7e03b2979569a8440a6e69b0285ac32
Reviewed-on: https://review.coreboot.org/c/coreboot/+/59738
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>

payloads/libpayload/include/libpayload.h

@@ -457,6 +457,8 @@ static inline int clz(u32 x)
 static inline int log2(u32 x) { return (int)sizeof(x) * 8 - clz(x) - 1; }
 /* Find First Set: __ffs(0xf) == 0, __ffs(0) == -1, __ffs(1 << 31) == 31 */
 static inline int __ffs(u32 x) { return log2(x & (u32)(-(s32)x)); }
+/* Find Last Set: __fls(1) == 0, __fls(5) == 2, __fls(1 << 31) == 31 */
+static inline int __fls(u32 x) { return log2(x); }
 
 static inline int popcnt64(u64 x) { return __builtin_popcountll(x); }
 static inline int clz64(u64 x)
@@ -466,6 +468,7 @@ static inline int clz64(u64 x)
 
 static inline int log2_64(u64 x) { return sizeof(x) * 8 - clz64(x) - 1; }
 static inline int __ffs64(u64 x) { return log2_64(x & (u64)(-(s64)x)); }
+static inline int __fls64(u64 x) { return log2_64(x); }
 /** @} */
 
 /**

src/commonlib/storage/sdhci.c

@@ -6,14 +6,15 @@
 #include "bouncebuf.h"
 #include <commonlib/sd_mmc_ctrlr.h>
 #include <commonlib/sdhci.h>
+#include <commonlib/stdlib.h>
 #include <commonlib/storage.h>
 #include <delay.h>
 #include <endian.h>
+#include <lib.h>
 #include "sdhci.h"
 #include "sd_mmc.h"
 #include "storage.h"
 #include <timer.h>
-#include <commonlib/stdlib.h>
 
 #define DMA_AVAILABLE	((CONFIG(SDHCI_ADMA_IN_BOOTBLOCK) && ENV_BOOTBLOCK) \
 			|| (CONFIG(SDHCI_ADMA_IN_VERSTAGE) && ENV_SEPARATE_VERSTAGE) \
@@ -411,36 +412,6 @@ static int sdhci_set_clock(struct sdhci_ctrlr *sdhci_ctrlr, unsigned int clock)
 	return 0;
 }
 
-/* Find leftmost set bit in a 32 bit integer */
-static int fls(u32 x)
-{
-	int r = 32;
-
-	if (!x)
-		return 0;
-	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;
-}
-
 static void sdhci_set_power(struct sdhci_ctrlr *sdhci_ctrlr,
 	unsigned short power)
 {
@@ -718,7 +689,7 @@ static int sdhci_init(struct sdhci_ctrlr *sdhci_ctrlr)
 	if (rv)
 		return rv; /* The error has been already reported */
 
-	sdhci_set_power(sdhci_ctrlr, fls(ctrlr->voltages) - 1);
+	sdhci_set_power(sdhci_ctrlr, __fls(ctrlr->voltages));
 
 	if (ctrlr->caps & DRVR_CAP_NO_CD) {
 		unsigned int status;

src/include/lib.h

@@ -53,6 +53,8 @@ static inline int clz(u32 x) { return x ? __builtin_clz(x) : sizeof(x) * 8; }
 static inline int log2(u32 x) { return sizeof(x) * 8 - clz(x) - 1; }
 /* Find First Set: __ffs(1) == 0, __ffs(0) == -1, __ffs(1<<31) == 31 */
 static inline int __ffs(u32 x) { return log2(x & (u32)(-(s32)x)); }
+/* Find Last Set: __fls(1) == 0, __fls(5) == 2, __fls(1 << 31) == 31 */
+static inline int __fls(u32 x) { return log2(x); }
 
 /* Integer binary logarithm (rounding up): log2_ceil(0) == -1, log2_ceil(5) == 3 */
 static inline int log2_ceil(u32 x) { return (x == 0) ? -1 : log2(x - 1) + 1; }
@@ -61,5 +63,6 @@ static inline int popcnt64(u64 x) { return __builtin_popcountll(x); }
 static inline int clz64(u64 x) { return x ? __builtin_clzll(x) : sizeof(x) * 8; }
 static inline int log2_64(u64 x) { return sizeof(x) * 8 - clz64(x) - 1; }
 static inline int __ffs64(u64 x) { return log2_64(x & (u64)(-(s64)x)); }
+static inline int __fls64(u64 x) { return log2_64(x); }
 
 #endif /* __LIB_H__ */

tests/lib/lib-test.c

@@ -37,6 +37,15 @@ void test_ffs(void **state)
 	assert_int_equal(__ffs(0xffffffff), 0);
 }
 
+void test_fls(void **state)
+{
+	assert_int_equal(__fls(0x0), -1);
+	assert_int_equal(__fls(0x1), 0);
+	assert_int_equal(__fls(0x5), 2);
+	assert_int_equal(__fls(0x80000000), 31);
+	assert_int_equal(__fls(0xffffffff), 31);
+}
+
 void test_log2_ceil(void **state)
 {
 	assert_int_equal(log2_ceil(0x0), -1);
@@ -53,6 +62,7 @@ int main(void)
 		cmocka_unit_test(test_clz),
 		cmocka_unit_test(test_log2),
 		cmocka_unit_test(test_ffs),
+		cmocka_unit_test(test_fls),
 		cmocka_unit_test(test_log2_ceil),
 	};