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-rw-r--r--users/fogti/store-ref-scanner/src/hbm.rs167
1 files changed, 167 insertions, 0 deletions
diff --git a/users/fogti/store-ref-scanner/src/hbm.rs b/users/fogti/store-ref-scanner/src/hbm.rs
new file mode 100644
index 000000000000..2520efd8363d
--- /dev/null
+++ b/users/fogti/store-ref-scanner/src/hbm.rs
@@ -0,0 +1,167 @@
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
+pub struct HalfBytesMask(pub [u8; 16]);
+
+#[allow(clippy::as_conversions, clippy::zero_prefixed_literal)]
+impl HalfBytesMask {
+    pub const B32_REVSHA256: HalfBytesMask =
+        HalfBytesMask([0, 0, 0, 0, 0, 0, 255, 3, 0, 0, 0, 0, 222, 127, 207, 7]);
+
+    pub const B64_BLAKE2B256: HalfBytesMask = HalfBytesMask([
+        0, 0, 0, 0, 0, 8, 255, 3, 254, 255, 255, 135, 254, 255, 255, 7,
+    ]);
+
+    pub const DFL_REST: HalfBytesMask = HalfBytesMask([
+        0, 0, 0, 0, 0, 104, 255, 163, 254, 255, 255, 135, 254, 255, 255, 7,
+    ]);
+
+    #[inline]
+    pub const fn from_expanded(x: [bool; 128]) -> Self {
+        let mut ret = [0u8; 16];
+        let mut idx = 0;
+        while idx < 16 {
+            let fin = idx * 8;
+            let mut idx2 = 0;
+            while idx2 < 8 {
+                if x[fin + idx2] {
+                    ret[idx] += (1 << idx2) as u8;
+                }
+                idx2 += 1;
+            }
+            idx += 1;
+        }
+        Self(ret)
+    }
+
+    /// create a mask by allowing all characters via the mask which are included in the given string
+    pub fn from_bytes(s: &[u8]) -> Self {
+        s.iter().fold(Self([0u8; 16]), |mut ret, &i| {
+            ret.set(i, true);
+            ret
+        })
+    }
+
+    pub const fn into_expanded(self) -> [bool; 128] {
+        let Self(ihbm) = self;
+        let mut ret = [false; 128];
+        let mut idx = 0;
+        while idx < 16 {
+            let fin = idx * 8;
+            let curi = ihbm[idx];
+            let mut idx2 = 0;
+            while idx2 < 8 {
+                ret[fin + idx2] = (curi >> idx2) & 0b1 != 0;
+                idx2 += 1;
+            }
+            idx += 1;
+        }
+        ret
+    }
+
+    pub fn contains(&self, byte: u8) -> bool {
+        if byte >= 0x80 {
+            false
+        } else {
+            (self.0[usize::from(byte / 8)] >> u32::from(byte % 8)) & 0b1 != 0
+        }
+    }
+
+    pub fn set(&mut self, byte: u8, allow: bool) {
+        if byte >= 0x80 {
+            if cfg!(debug_assertions) {
+                panic!(
+                    "tried to manipulate invalid byte {:?} in HalfBytesMask",
+                    byte
+                );
+            } else {
+                return;
+            }
+        }
+        let block = &mut self.0[usize::from(byte / 8)];
+        let bitpat = (1 << u32::from(byte % 8)) as u8;
+        if allow {
+            *block |= bitpat;
+        } else {
+            *block &= !bitpat;
+        }
+    }
+
+    #[cfg(test)]
+    fn count_ones(&self) -> u8 {
+        self.0
+            .iter()
+            .map(|i| i.count_ones())
+            .sum::<u32>()
+            .try_into()
+            .unwrap()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn maskbase() {
+        assert_eq!(HalfBytesMask::B32_REVSHA256.count_ones(), 32);
+        assert_eq!(HalfBytesMask::B64_BLAKE2B256.count_ones(), 64);
+    }
+
+    #[test]
+    fn non_ascii() {
+        for i in 0x80..=0xff {
+            assert!(!HalfBytesMask::DFL_REST.contains(i));
+        }
+    }
+
+    #[test]
+    fn dflmask() {
+        assert_eq!(
+            HalfBytesMask::from_expanded(
+                [
+                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+                ]
+                .map(|i| i != 0)
+            ),
+            Default::default(),
+        );
+
+        assert_eq!(
+            HalfBytesMask::from_expanded(
+                [
+                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1,
+                    1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1,
+                    1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0,
+                ]
+                .map(|i| i != 0)
+            ),
+            HalfBytesMask::B32_REVSHA256,
+        );
+
+        assert_eq!(
+            HalfBytesMask::from_expanded(
+                [
+                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1,
+                    1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+                    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1,
+                    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0,
+                ]
+                .map(|i| i != 0)
+            ),
+            HalfBytesMask::B64_BLAKE2B256,
+        );
+
+        assert_eq!(
+            HalfBytesMask::from_bytes(
+                b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+-._?="
+            ),
+            HalfBytesMask::DFL_REST,
+        );
+    }
+}