80 lines
1.0 KiB
C
80 lines
1.0 KiB
C
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#ifndef __OS_FFS_H_
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#define __OS_FFS_H_
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#if 0
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#ifdef __cplusplus
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extern "C" {
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#endif
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static inline int ffs(int x)
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{
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int r = 1;
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if (!x) {
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return 0;
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}
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if (!(x & 0xffff)) {
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x >>= 16;
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r += 16;
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}
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if (!(x & 0xff)) {
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x >>= 8;
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r += 8;
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}
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if (!(x & 0xf)) {
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x >>= 4;
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r += 4;
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}
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if (!(x & 3)) {
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x >>= 2;
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r += 2;
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}
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if (!(x & 1)) {
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x >>= 1;
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r += 1;
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}
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return r;
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}
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static inline int fls(int x)
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{
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int r = 32;
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if (!x) {
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return 0;
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}
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if (!(x & 0xffff0000u)) {
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x <<= 16;
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r -= 16;
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}
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if (!(x & 0xff000000u)) {
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x <<= 8;
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r -= 8;
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}
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if (!(x & 0xf0000000u)) {
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x <<= 4;
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r -= 4;
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}
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if (!(x & 0xc0000000u)) {
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x <<= 2;
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r -= 2;
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}
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if (!(x & 0x80000000u)) {
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x <<= 1;
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r -= 1;
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}
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return r;
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}
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#ifdef __cplusplus
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}
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#endif
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#else
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int ffs(int x);
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int fls(int x);
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#endif
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#endif
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