NASM 2.11

[platform/upstream/nasm.git] / ilog2.c

diff --git a/ilog2.c b/ilog2.c
index 3a0b4a4..9c054fd 100644 (file)
--- a/ilog2.c
+++ b/ilog2.c
@@ -34,15 +34,23 @@
 #include "compiler.h"
 #include "nasmlib.h"
 
+#define ROUND(v, a, w)                      \
+    do {                                    \
+        if (v & (((1 << w) - 1) << w)) {    \
+            a  += w;                        \
+            v >>= w;                        \
+        }                                   \
+    } while (0)
+
 #if defined(__GNUC__) && defined(__x86_64__)
 
 int ilog2_32(uint32_t v)
 {
     int n;
 
-    __asm__("bsrl %1,%0 ; cmovel %2,%0"
-           : "=&r" (n)
-           : "rm" (v), "rm" (0));
+    __asm__("bsrl %1,%0"
+            : "=r" (n)
+            : "rm" (v), "0" (0));
     return n;
 }
 
@@ -53,9 +61,9 @@ int ilog2_32(uint32_t v)
     int n;
 
     __asm__("bsrl %1,%0 ; jnz 1f ; xorl %0,%0\n"
-           "1:"
-           : "=&r" (n)
-           : "rm" (v));
+            "1:"
+            : "=&r" (n)
+            : "rm" (v));
     return n;
 }
 
@@ -64,39 +72,24 @@ int ilog2_32(uint32_t v)
 int ilog2_32(uint32_t v)
 {
     if (!v)
-       return 0;
-    else
-       return __builtin_clz(v) ^ 31;
+        return 0;
+
+    return __builtin_clz(v) ^ 31;
 }
 
 #else
 
 int ilog2_32(uint32_t v)
 {
-       int p = 0;
-
-       if (v & 0xffff0000) {
-               p += 16;
-               v >>= 16;
-       }
-       if (v & 0xff00) {
-               p += 8;
-               v >>= 8;
-       }
-       if (v & 0xf0) {
-               p += 4;
-               v >>= 4;
-       }
-       if (v & 0xc) {
-               p += 2;
-               v >>= 2;
-       }
-       if (v & 0x2) {
-               p += 1;
-               v >>= 1;
-       }
-
-       return p;
+    int p = 0;
+
+    ROUND(v, p, 16);
+    ROUND(v, p,  8);
+    ROUND(v, p,  4);
+    ROUND(v, p,  2);
+    ROUND(v, p,  1);
+
+    return p;
 }
 
 #endif
@@ -107,9 +100,9 @@ int ilog2_64(uint64_t v)
 {
     uint64_t n;
 
-    __asm__("bsrq %1,%0 ; cmoveq %2,%0"
-           : "=&r" (n)
-           : "rm" (v), "rm" (UINT64_C(0)));
+    __asm__("bsrq %1,%0"
+            : "=r" (n)
+            : "rm" (v), "0" (UINT64_C(0)));
     return n;
 }
 
@@ -118,45 +111,31 @@ int ilog2_64(uint64_t v)
 int ilog2_64(uint64_t v)
 {
     if (!v)
-       return 0;
-    else
-       return __builtin_clzll(v) ^ 63;
+        return 0;
+
+    return __builtin_clzll(v) ^ 63;
 }
 
 #else
 
 int ilog2_64(uint64_t vv)
 {
-       int p = 0;
-       uint32_t v;
-
-       if ((v = vv >> 32) != 0) {
-           p += 32;
-       } else {
-           v = vv;
-       }
-       if (v & 0xffff0000) {
-               p += 16;
-               v >>= 16;
-       }
-       if (v & 0xff00) {
-               p += 8;
-               v >>= 8;
-       }
-       if (v & 0xf0) {
-               p += 4;
-               v >>= 4;
-       }
-       if (v & 0xc) {
-               p += 2;
-               v >>= 2;
-       }
-       if (v & 0x2) {
-               p += 1;
-               v >>= 1;
-       }
-
-       return p;
+    int p = 0;
+    uint32_t v;
+
+    v = vv >> 32;
+    if (v)
+        p += 32;
+    else
+        v = vv;
+
+    ROUND(v, p, 16);
+    ROUND(v, p,  8);
+    ROUND(v, p,  4);
+    ROUND(v, p,  2);
+    ROUND(v, p,  1);
+
+    return p;
 }
 
 #endif
@@ -167,7 +146,7 @@ int ilog2_64(uint64_t vv)
 int alignlog2_32(uint32_t v)
 {
     if (unlikely(v & (v-1)))
-       return -1;              /* invalid alignment */
+        return -1;              /* invalid alignment */
 
     return ilog2_32(v);
 }
@@ -175,7 +154,7 @@ int alignlog2_32(uint32_t v)
 int alignlog2_64(uint64_t v)
 {
     if (unlikely(v & (v-1)))
-       return -1;              /* invalid alignment */
+        return -1;              /* invalid alignment */
 
     return ilog2_64(v);
 }