From 3a3f06b05eee7c3e9da781864a510eda1ff587b8 Mon Sep 17 00:00:00 2001
From: "Ronald S. Bultje" <rsbultje@gmail.com>
Date: Sun, 18 Mar 2012 19:33:04 -0700
Subject: dpcm: convert to bytestream2.

---
 libavcodec/dpcm.c | 58 +++++++++++++++++++++++++++++--------------------------
 1 file changed, 31 insertions(+), 27 deletions(-)

(limited to 'libavcodec/dpcm.c')

diff --git a/libavcodec/dpcm.c b/libavcodec/dpcm.c
index 7f5dbfe3b9..2bd7978317 100644
--- a/libavcodec/dpcm.c
+++ b/libavcodec/dpcm.c
@@ -40,6 +40,7 @@
 #include "libavutil/intreadwrite.h"
 #include "avcodec.h"
 #include "bytestream.h"
+#include "mathops.h"
 
 typedef struct DPCMContext {
     AVFrame frame;
@@ -173,20 +174,18 @@ static av_cold int dpcm_decode_init(AVCodecContext *avctx)
 static int dpcm_decode_frame(AVCodecContext *avctx, void *data,
                              int *got_frame_ptr, AVPacket *avpkt)
 {
-    const uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;
-    const uint8_t *buf_end = buf + buf_size;
     DPCMContext *s = avctx->priv_data;
     int out = 0, ret;
     int predictor[2];
     int ch = 0;
     int stereo = s->channels - 1;
-    int16_t *output_samples;
+    int16_t *output_samples, *samples_end;
+    GetByteContext gb;
 
-    if (stereo && (buf_size & 1)) {
+    if (stereo && (buf_size & 1))
         buf_size--;
-        buf_end--;
-    }
+    bytestream2_init(&gb, avpkt->data, buf_size);
 
     /* calculate output size */
     switch(avctx->codec->id) {
@@ -218,22 +217,23 @@ static int dpcm_decode_frame(AVCodecContext *avctx, void *data,
         return ret;
     }
     output_samples = (int16_t *)s->frame.data[0];
+    samples_end = output_samples + out;
 
     switch(avctx->codec->id) {
 
     case CODEC_ID_ROQ_DPCM:
-        buf += 6;
+        bytestream2_skipu(&gb, 6);
 
         if (stereo) {
-            predictor[1] = (int16_t)(bytestream_get_byte(&buf) << 8);
-            predictor[0] = (int16_t)(bytestream_get_byte(&buf) << 8);
+            predictor[1] = sign_extend(bytestream2_get_byteu(&gb) << 8, 16);
+            predictor[0] = sign_extend(bytestream2_get_byteu(&gb) << 8, 16);
         } else {
-            predictor[0] = (int16_t)bytestream_get_le16(&buf);
+            predictor[0] = sign_extend(bytestream2_get_le16u(&gb), 16);
         }
 
         /* decode the samples */
-        while (buf < buf_end) {
-            predictor[ch] += s->roq_square_array[*buf++];
+        while (output_samples < samples_end) {
+            predictor[ch] += s->roq_square_array[bytestream2_get_byteu(&gb)];
             predictor[ch]  = av_clip_int16(predictor[ch]);
             *output_samples++ = predictor[ch];
 
@@ -243,16 +243,16 @@ static int dpcm_decode_frame(AVCodecContext *avctx, void *data,
         break;
 
     case CODEC_ID_INTERPLAY_DPCM:
-        buf += 6;  /* skip over the stream mask and stream length */
+        bytestream2_skipu(&gb, 6);  /* skip over the stream mask and stream length */
 
         for (ch = 0; ch < s->channels; ch++) {
-            predictor[ch] = (int16_t)bytestream_get_le16(&buf);
+            predictor[ch] = sign_extend(bytestream2_get_le16u(&gb), 16);
             *output_samples++ = predictor[ch];
         }
 
         ch = 0;
-        while (buf < buf_end) {
-            predictor[ch] += interplay_delta_table[*buf++];
+        while (output_samples < samples_end) {
+            predictor[ch] += interplay_delta_table[bytestream2_get_byteu(&gb)];
             predictor[ch]  = av_clip_int16(predictor[ch]);
             *output_samples++ = predictor[ch];
 
@@ -266,16 +266,19 @@ static int dpcm_decode_frame(AVCodecContext *avctx, void *data,
         int shift[2] = { 4, 4 };
 
         for (ch = 0; ch < s->channels; ch++)
-            predictor[ch] = (int16_t)bytestream_get_le16(&buf);
+            predictor[ch] = sign_extend(bytestream2_get_le16u(&gb), 16);
 
         ch = 0;
-        while (buf < buf_end) {
-            uint8_t n = *buf++;
-            int16_t diff = (n & 0xFC) << 8;
-            if ((n & 0x03) == 3)
+        while (output_samples < samples_end) {
+            int diff = bytestream2_get_byteu(&gb);
+            int n    = diff & 3;
+
+            if (n == 3)
                 shift[ch]++;
             else
-                shift[ch] -= (2 * (n & 3));
+                shift[ch] -= (2 * n);
+            diff = sign_extend((diff &~ 3) << 8, 16);
+
             /* saturate the shifter to a lower limit of 0 */
             if (shift[ch] < 0)
                 shift[ch] = 0;
@@ -293,9 +296,10 @@ static int dpcm_decode_frame(AVCodecContext *avctx, void *data,
     }
     case CODEC_ID_SOL_DPCM:
         if (avctx->codec_tag != 3) {
-            uint8_t *output_samples_u8 = s->frame.data[0];
-            while (buf < buf_end) {
-                uint8_t n = *buf++;
+            uint8_t *output_samples_u8 = s->frame.data[0],
+                    *samples_end_u8 = output_samples_u8 + out;
+            while (output_samples_u8 < samples_end_u8) {
+                int n = bytestream2_get_byteu(&gb);
 
                 s->sample[0] += s->sol_table[n >> 4];
                 s->sample[0]  = av_clip_uint8(s->sample[0]);
@@ -306,8 +310,8 @@ static int dpcm_decode_frame(AVCodecContext *avctx, void *data,
                 *output_samples_u8++ = s->sample[stereo];
             }
         } else {
-            while (buf < buf_end) {
-                uint8_t n = *buf++;
+            while (output_samples < samples_end) {
+                int n = bytestream2_get_byteu(&gb);
                 if (n & 0x80) s->sample[ch] -= sol_table_16[n & 0x7F];
                 else          s->sample[ch] += sol_table_16[n & 0x7F];
                 s->sample[ch] = av_clip_int16(s->sample[ch]);
-- 
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