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Add check for power of 2 to std.mem.alignBackward

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This commit is contained in:
SamTebbs33 2019-06-27 22:23:09 +01:00
parent 14abf0fda5
commit 623dbb73df
1 changed files with 4 additions and 3 deletions
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7
std/mem.zig
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@ -1481,7 +1481,7 @@ test "subArrayPtr" {
} }
/// Round an address up to the nearest aligned address /// Round an address up to the nearest aligned address
/// The alignment must be greater than 0. /// The alignment must be a power of 2 and greater than 0.
pub fn alignForward(addr: usize, alignment: usize) usize { pub fn alignForward(addr: usize, alignment: usize) usize {
return alignBackward(addr + (alignment - 1), alignment); return alignBackward(addr + (alignment - 1), alignment);
} }
@ -1502,8 +1502,9 @@ test "alignForward" {
} }
/// Round an address up to the previous aligned address /// Round an address up to the previous aligned address
/// The alignment must be greater than 0. /// The alignment must be a power of 2 and greater than 0.
pub fn alignBackward(addr: usize, alignment: usize) usize { pub fn alignBackward(addr: usize, alignment: usize) usize {
assert(@popCount(usize, alignment) == 1);
// 000010000 // example addr // 000010000 // example addr
// 000001111 // subtract 1 // 000001111 // subtract 1
// 111110000 // binary not // 111110000 // binary not
@ -1511,7 +1512,7 @@ pub fn alignBackward(addr: usize, alignment: usize) usize {
} }
/// Given an address and an alignment, return true if the address is a multiple of the alignment /// Given an address and an alignment, return true if the address is a multiple of the alignment
/// The alignment must be greater than 0. /// The alignment must be a power of 2 and greater than 0.
pub fn isAligned(addr: usize, alignment: usize) bool { pub fn isAligned(addr: usize, alignment: usize) bool {
return alignBackward(addr, alignment) == addr; return alignBackward(addr, alignment) == addr;
} }