refactor: make silk_stereo_decode_pred and silk_stereo_decode_mid_only safe

Author: DCNick3

src/silk/dec_API.rs

@@ -43,15 +43,15 @@ pub struct silk_decoder {
     pub sStereo: stereo_dec_state,
     pub nChannelsAPI: i32,
     pub nChannelsInternal: i32,
-    pub prev_decode_only_middle: i32,
+    pub prev_decode_only_middle: bool,
 }
 pub fn silk_InitDecoder() -> silk_decoder {
     silk_decoder {
         channel_state: [silk_init_decoder(), silk_init_decoder()],
         sStereo: stereo_dec_state::default(),
         nChannelsAPI: 0,
         nChannelsInternal: 0,
-        prev_decode_only_middle: 0,
+        prev_decode_only_middle: false,
     }
 }
 pub unsafe fn silk_Decode(
@@ -66,7 +66,7 @@ pub unsafe fn silk_Decode(
 ) -> i32 {
     let mut i: i32 = 0;
     let mut n: i32 = 0;
-    let mut decode_only_middle: i32 = 0;
+    let mut decode_only_middle: bool = false;
     let mut ret: i32 = SILK_NO_ERROR;
     let mut nSamplesOutDec: i32 = 0;
     let mut LBRR_symbol: i32 = 0;
@@ -203,7 +203,7 @@ pub unsafe fn silk_Decode(
                         let mut pulses: [i16; 320] = [0; 320];
                         let mut condCoding: i32 = 0;
                         if decControl.nChannelsInternal == 2 && n == 0 {
-                            silk_stereo_decode_pred(psRangeDec, MS_pred_Q13.as_mut_ptr());
+                            silk_stereo_decode_pred(psRangeDec, &mut MS_pred_Q13);
                             if channel_state[1].LBRR_flags[i as usize] == 0 {
                                 silk_stereo_decode_mid_only(psRangeDec, &mut decode_only_middle);
                             }
@@ -247,15 +247,15 @@ pub unsafe fn silk_Decode(
             || lostFlag == FLAG_DECODE_LBRR
                 && channel_state[0].LBRR_flags[channel_state[0].nFramesDecoded as usize] == 1
         {
-            silk_stereo_decode_pred(psRangeDec, MS_pred_Q13.as_mut_ptr());
+            silk_stereo_decode_pred(psRangeDec, &mut MS_pred_Q13);
             if lostFlag == FLAG_DECODE_NORMAL
                 && channel_state[1].VAD_flags[channel_state[0].nFramesDecoded as usize] == 0
                 || lostFlag == FLAG_DECODE_LBRR
                     && channel_state[1].LBRR_flags[channel_state[0].nFramesDecoded as usize] == 0
             {
                 silk_stereo_decode_mid_only(psRangeDec, &mut decode_only_middle);
             } else {
-                decode_only_middle = 0;
+                decode_only_middle = false;
             }
         } else {
             n = 0;
@@ -266,8 +266,8 @@ pub unsafe fn silk_Decode(
         }
     }
     if decControl.nChannelsInternal == 2
-        && decode_only_middle == 0
-        && psDec.prev_decode_only_middle == 1
+        && decode_only_middle == false
+        && psDec.prev_decode_only_middle == true
     {
         memset(
             (channel_state[1].outBuf).as_mut_ptr() as *mut core::ffi::c_void,
@@ -305,9 +305,9 @@ pub unsafe fn silk_Decode(
             .offset(2 as isize);
     }
     if lostFlag == FLAG_DECODE_NORMAL {
-        has_side = (decode_only_middle == 0) as i32;
+        has_side = (decode_only_middle == false) as i32;
     } else {
-        has_side = (psDec.prev_decode_only_middle == 0
+        has_side = (psDec.prev_decode_only_middle == false
             || decControl.nChannelsInternal == 2
                 && lostFlag == FLAG_DECODE_LBRR
                 && channel_state[1].LBRR_flags[channel_state[1].nFramesDecoded as usize] == 1)
@@ -328,7 +328,7 @@ pub unsafe fn silk_Decode(
                     } else {
                         CODE_INDEPENDENTLY
                     };
-            } else if n > 0 && psDec.prev_decode_only_middle != 0 {
+            } else if n > 0 && psDec.prev_decode_only_middle != false {
                 condCoding_0 = CODE_INDEPENDENTLY_NO_LTP_SCALING;
             } else {
                 condCoding_0 = CODE_CONDITIONALLY;

src/silk/stereo_decode_pred.rs

@@ -1,38 +1,58 @@
 use crate::celt::entdec::{ec_dec, ec_dec_icdf};
+use crate::silk::define::STEREO_QUANT_SUB_STEPS;
+use crate::silk::macros::silk_SMULWB;
 use crate::silk::tables_other::{
     silk_stereo_only_code_mid_iCDF, silk_stereo_pred_joint_iCDF, silk_stereo_pred_quant_Q13,
     silk_uniform3_iCDF, silk_uniform5_iCDF,
 };
+use crate::silk::SigProc_FIX::SILK_FIX_CONST;
 
-pub unsafe fn silk_stereo_decode_pred(psRangeDec: &mut ec_dec, pred_Q13: *mut i32) {
-    let mut n: i32 = 0;
-    let mut ix: [[i32; 3]; 2] = [[0; 3]; 2];
-    let mut low_Q13: i32 = 0;
-    let mut step_Q13: i32 = 0;
-    n = ec_dec_icdf(psRangeDec, &silk_stereo_pred_joint_iCDF, 8);
-    ix[0 as usize][2 as usize] = n / 5;
-    ix[1 as usize][2 as usize] = n - 5 * ix[0 as usize][2 as usize];
-    n = 0;
+/// Decode mid/side predictors
+///
+/// ```text
+/// psRangeDec    I/O   Compressor data structure
+/// pred_Q13[]    O     Predictors
+/// ```
+pub fn silk_stereo_decode_pred(psRangeDec: &mut ec_dec, pred_Q13: &mut [i32; 2]) {
+    let n = ec_dec_icdf(psRangeDec, &silk_stereo_pred_joint_iCDF, 8) as usize;
+
+    let mut ix: [[usize; 3]; 2] = [[0; 3]; 2];
+    ix[0][2] = n / 5;
+    ix[1][2] = n - 5 * ix[0][2];
+
+    /* Entropy decoding */
+    let mut n = 0;
     while n < 2 {
-        ix[n as usize][0 as usize] = ec_dec_icdf(psRangeDec, &silk_uniform3_iCDF, 8);
-        ix[n as usize][1 as usize] = ec_dec_icdf(psRangeDec, &silk_uniform5_iCDF, 8);
+        ix[n][0] = ec_dec_icdf(psRangeDec, &silk_uniform3_iCDF, 8) as usize;
+        ix[n][1] = ec_dec_icdf(psRangeDec, &silk_uniform5_iCDF, 8) as usize;
         n += 1;
     }
-    n = 0;
+
+    /* Dequantize */
+    let mut n = 0;
     while n < 2 {
-        ix[n as usize][0 as usize] += 3 * ix[n as usize][2 as usize];
-        low_Q13 = silk_stereo_pred_quant_Q13[ix[n as usize][0 as usize] as usize] as i32;
-        step_Q13 = ((silk_stereo_pred_quant_Q13[(ix[n as usize][0 as usize] + 1) as usize] as i32
-            - low_Q13) as i64
-            * (0.5f64 / 5 as f64 * ((1) << 16) as f64 + 0.5f64) as i32 as i16 as i64
-            >> 16) as i32;
-        *pred_Q13.offset(n as isize) =
-            low_Q13 + step_Q13 as i16 as i32 * (2 * ix[n as usize][1 as usize] + 1) as i16 as i32;
+        ix[n][0] += 3 * ix[n][2];
+        let low_Q13 = silk_stereo_pred_quant_Q13[ix[n][0]] as i32;
+        let step_Q13 = silk_SMULWB(
+            (silk_stereo_pred_quant_Q13[ix[n][0] + 1] as i32 - low_Q13),
+            SILK_FIX_CONST!(0.5 / STEREO_QUANT_SUB_STEPS as f64, 16),
+        );
+
+        pred_Q13[n] = low_Q13 + step_Q13 as i16 as i32 * (2 * ix[n][1] + 1) as i16 as i32;
         n += 1;
     }
-    let ref mut fresh0 = *pred_Q13.offset(0 as isize);
-    *fresh0 -= *pred_Q13.offset(1 as isize);
+
+    /* Subtract second from first predictor (helps when actually applying these) */
+    pred_Q13[0] -= pred_Q13[1];
 }
-pub unsafe fn silk_stereo_decode_mid_only(psRangeDec: &mut ec_dec, decode_only_mid: *mut i32) {
-    *decode_only_mid = ec_dec_icdf(psRangeDec, &silk_stereo_only_code_mid_iCDF, 8);
+
+/// Decode mid-only flag
+///
+/// ```text
+/// psRangeDec        I/O   Compressor data structure
+/// decode_only_mid   O     Flag that only mid channel has been coded
+/// ```
+pub fn silk_stereo_decode_mid_only(psRangeDec: &mut ec_dec, decode_only_mid: &mut bool) {
+    /* Decode flag that only mid channel is coded */
+    *decode_only_mid = ec_dec_icdf(psRangeDec, &silk_stereo_only_code_mid_iCDF, 8) != 0;
 }