Remove lookup table from rustc-std builds

Frommi · May 16, 2024 · f06ec4b · f06ec4b
1 parent 35c71e1
commit f06ec4b
Showing 1 changed file with 20 additions and 10 deletions.
diff --git a/miniz_oxide/src/inflate/core.rs b/miniz_oxide/src/inflate/core.rs
@@ -678,17 +678,27 @@ fn start_static_table(r: &mut DecompressorOxide) {
     memset(&mut r.tables[DIST_TABLE].code_size[0..32], 5);
 }
 
-static REVERSED_BITS_LOOKUP: [u32; 1024] = {
-    let mut table = [0; 1024];
+#[cfg(feature = "rustc-dep-of-std")]
+fn reverse_bits(n: u32) -> u32 {
+    n.reverse_bits()
+}
 
-    let mut i = 0;
-    while i < 1024 {
-        table[i] = (i as u32).reverse_bits();
-        i += 1;
-    }
+#[cfg(not(feature = "rustc-dep-of-std"))]
+fn reverse_bits(n: u32) -> u32 {
+    static REVERSED_BITS_LOOKUP: [u32; 1024] = {
+        let mut table = [0; 1024];
+
+        let mut i = 0;
+        while i < 1024 {
+            table[i] = (i as u32).reverse_bits();
+            i += 1;
+        }
 
-    table
-};
+        table
+    };
+
+    REVERSED_BITS_LOOKUP[n as usize]
+}
 
 fn init_tree(r: &mut DecompressorOxide, l: &mut LocalVars) -> Option<Action> {
     loop {
@@ -746,7 +756,7 @@ fn init_tree(r: &mut DecompressorOxide, l: &mut LocalVars) -> Option<Action> {
             let n = cur_code & (u32::MAX >> (32 - code_size));
 
             let mut rev_code = if n < 1024 {
-                REVERSED_BITS_LOOKUP[n as usize] >> (32 - code_size)
+                reverse_bits(n) >> (32 - code_size)
             } else {
                 for _ in 0..code_size {
                     rev_code = (rev_code << 1) | (cur_code & 1);