static dav1d_scans: Make safe (i.e. non-mut) by using `static [u1…

…6]`s instead of `*const u16`s (#356)

Non-`mut` `static`s can't contain internal raw ptrs, so this is needed
to make it safe. All use sites implicitly coerce from slice to raw ptr.

See my suggestion for future work in
#354 (review);
it was simple so I just did it.

src/recon_tmpl_16.rs

@@ -52,7 +52,6 @@ extern "C" {
     );
     fn dav1d_copy_lpf_16bpc(f: *mut Dav1dFrameContext, src: *const *mut pixel, sby: libc::c_int);
     fn dav1d_lr_sbrow_16bpc(f: *mut Dav1dFrameContext, dst: *const *mut pixel, sby: libc::c_int);
-    static dav1d_scans: [*const uint16_t; 19];
     static mut dav1d_wedge_masks: [[[[*const uint8_t; 16]; 2]; 3]; 22];
     static mut dav1d_ii_masks: [[[*const uint8_t; 4]; 3]; 22];
 }
@@ -63,11 +62,11 @@ use crate::src::msac::dav1d_msac_decode_hi_tok;
 use crate::src::msac::dav1d_msac_decode_symbol_adapt16;
 use crate::src::msac::dav1d_msac_decode_symbol_adapt4;
 use crate::src::msac::dav1d_msac_decode_symbol_adapt8;
+use crate::src::scan::dav1d_scans;
 use crate::src::tables::dav1d_block_dimensions;
 use crate::src::tables::dav1d_filter_2d;
 use crate::src::tables::dav1d_filter_mode_to_y_mode;
 use crate::src::tables::dav1d_lo_ctx_offsets;
-
 use crate::src::tables::dav1d_tx_type_class;
 use crate::src::tables::dav1d_tx_types_per_set;
 use crate::src::tables::dav1d_txfm_dimensions;
@@ -1013,7 +1012,7 @@ unsafe fn decode_coefs(
                     &dav1d_lo_ctx_offsets
                         [nonsquare_tx.wrapping_add(tx as libc::c_uint & nonsquare_tx) as usize],
                 );
-                scan = dav1d_scans[tx as usize];
+                scan = dav1d_scans[tx as usize].as_ptr();
                 let stride: ptrdiff_t = (4 * sh) as ptrdiff_t;
                 let shift: libc::c_uint = (if ((*t_dim).lh as libc::c_int) < 4 {
                     (*t_dim).lh as libc::c_int + 2

src/recon_tmpl_8.rs

@@ -51,7 +51,6 @@ extern "C" {
     );
     fn dav1d_copy_lpf_8bpc(f: *mut Dav1dFrameContext, src: *const *mut pixel, sby: libc::c_int);
     fn dav1d_lr_sbrow_8bpc(f: *mut Dav1dFrameContext, dst: *const *mut pixel, sby: libc::c_int);
-    static dav1d_scans: [*const uint16_t; 19];
     static mut dav1d_wedge_masks: [[[[*const uint8_t; 16]; 2]; 3]; 22];
     static mut dav1d_ii_masks: [[[*const uint8_t; 4]; 3]; 22];
 }
@@ -62,11 +61,11 @@ use crate::src::msac::dav1d_msac_decode_hi_tok;
 use crate::src::msac::dav1d_msac_decode_symbol_adapt16;
 use crate::src::msac::dav1d_msac_decode_symbol_adapt4;
 use crate::src::msac::dav1d_msac_decode_symbol_adapt8;
+use crate::src::scan::dav1d_scans;
 use crate::src::tables::dav1d_block_dimensions;
 use crate::src::tables::dav1d_filter_2d;
 use crate::src::tables::dav1d_filter_mode_to_y_mode;
 use crate::src::tables::dav1d_lo_ctx_offsets;
-
 use crate::src::tables::dav1d_tx_type_class;
 use crate::src::tables::dav1d_tx_types_per_set;
 use crate::src::tables::dav1d_txfm_dimensions;
@@ -986,7 +985,7 @@ unsafe fn decode_coefs(
                     &dav1d_lo_ctx_offsets
                         [nonsquare_tx.wrapping_add(tx as libc::c_uint & nonsquare_tx) as usize],
                 );
-                scan = dav1d_scans[tx as usize];
+                scan = dav1d_scans[tx as usize].as_ptr();
                 let stride: ptrdiff_t = (4 * sh) as ptrdiff_t;
                 let shift: libc::c_uint = (if ((*t_dim).lh as libc::c_int) < 4 {
                     (*t_dim).lh as libc::c_int + 2

src/scan.rs

@@ -199,25 +199,25 @@ static scan_32x32: Align32<[u16; 1024]> = Align32([
     986, 1017, 1018, 987, 956, 925, 894, 863, 895, 926, 957, 988, 1019, 1020, 989, 958, 927, 959,
     990, 1021, 1022, 991, 1023,
 ]);
-#[no_mangle]
-pub static mut dav1d_scans: [*const u16; 19] = [
-    scan_4x4.0.as_ptr(),
-    scan_8x8.0.as_ptr(),
-    scan_16x16.0.as_ptr(),
-    scan_32x32.0.as_ptr(),
-    scan_32x32.0.as_ptr(),
-    scan_4x8.0.as_ptr(),
-    scan_8x4.0.as_ptr(),
-    scan_8x16.0.as_ptr(),
-    scan_16x8.0.as_ptr(),
-    scan_16x32.0.as_ptr(),
-    scan_32x16.0.as_ptr(),
-    scan_32x32.0.as_ptr(),
-    scan_32x32.0.as_ptr(),
-    scan_4x16.0.as_ptr(),
-    scan_16x4.0.as_ptr(),
-    scan_8x32.0.as_ptr(),
-    scan_32x8.0.as_ptr(),
-    scan_16x32.0.as_ptr(),
-    scan_32x16.0.as_ptr(),
+
+pub static dav1d_scans: [&'static [u16]; 19] = [
+    &scan_4x4.0,
+    &scan_8x8.0,
+    &scan_16x16.0,
+    &scan_32x32.0,
+    &scan_32x32.0,
+    &scan_4x8.0,
+    &scan_8x4.0,
+    &scan_8x16.0,
+    &scan_16x8.0,
+    &scan_16x32.0,
+    &scan_32x16.0,
+    &scan_32x32.0,
+    &scan_32x32.0,
+    &scan_4x16.0,
+    &scan_16x4.0,
+    &scan_8x32.0,
+    &scan_32x8.0,
+    &scan_16x32.0,
+    &scan_32x16.0,
 ];