Fix round2

- don't limit it to 32 bits
- give it a proper name
- don't over-allocate too much

1 files changed, 29 insertions, 0 deletions

diff --git a/round2_32.go b/round2_32.go
new file mode 100644
index 0000000..541b85e
--- /dev/null
+++ b/round2_32.go
@@ -0,0 +1,29 @@
+//go:build !amd64 && !arm64 && !ppc64 && !ppc64le && !s390x
+// +build !amd64,!arm64,!ppc64,!ppc64le,!s390x
+
+package fasthttp
+
+func roundUpForSliceCap(n int) int {
+	if n <= 0 {
+		return 0
+	}
+
+	// Above 100MB, we don't round up as the overhead is too large.
+	if n > 100*1024*1024 {
+		return n
+	}
+
+	x := uint32(n - 1)
+	x |= x >> 1
+	x |= x >> 2
+	x |= x >> 4
+	x |= x >> 8
+	x |= x >> 16
+
+	// Make sure we don't return 0 due to overflow, even on 32 bit systems
+	if x >= uint32(math.MaxInt32) {
+		return math.MaxInt32
+	}
+
+	return int(x + 1)
+}