On Wed, 6 Apr 2022 18:22:45 GMT, John R Rose <jr...@openjdk.org> wrote:
>> Paul Sandoz has updated the pull request incrementally with two additional >> commits since the last revision: >> >> - Fix typo. >> - Provide examples. > > src/java.base/share/classes/java/lang/Integer.java line 1781: > >> 1779: * All the upper remaining bits of the compressed value are set >> 1780: * to zero. >> 1781: * > > Following Alan's comment, I suggest the following examples: > > > compress(0x9ABCDEF, 0x0F0F0FF) == 0xACEF > compress(x, 1<<n) == (x>>n & 1) > compress(x, -1<<n) == x >>> n > compress(m, m) == (m==-1||m==0)? m : (1<<bitCount(m))-1 > compress(x, m) == compress(x & m, m) > compress(expand(x, m), m) == x & compress(m, m) > (compress(x, m) >>> n) & 1 == /*the bit of x corresponding to the nth set > bit in m*/ > > > …In two places. Similarly, examples for expand: > > > expand(0x9ABCDEF, 0x0F0F0FF) == 0xC0D0EF > expand(x, 1<<n) == (x&1) << n > expand(x, -1<<n) == x << n > expand(-1, m) == m > expand(x, m) == expand(x, m) & m > expand(compress(x, m), m) == x & m > expand(1<<n, m) == /*the nth set bit in m, as a mask in place; cf. > highest/lowestOneBit*/ > > > (Please double check these examples!) Examples added in latest commit. ------------- PR: https://git.openjdk.java.net/jdk/pull/8115
