[FFmpeg-devel] [PATCH 3/7] avcodec/sgidec: Avoid redundant private context

[Andreas Rheinhardt <andreas.rheinhardt@outlook.com>]

SGI is intra-frame only; the decoder therefore does not
maintain any state between frames, so remove
the private context.

Also rename depth to nb_components.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
 libavcodec/sgidec.c | 158 ++++++++++++++++++++------------------------
 1 file changed, 73 insertions(+), 85 deletions(-)

diff --git a/libavcodec/sgidec.c b/libavcodec/sgidec.c
index a449859bf8..bd49a3510d 100644
--- a/libavcodec/sgidec.c
+++ b/libavcodec/sgidec.c
@@ -25,25 +25,17 @@
 #include "decode.h"
 #include "sgi.h"
 
-typedef struct SgiState {
-    AVCodecContext *avctx;
-    unsigned int width;
-    int height;
-    unsigned int depth;
-    unsigned int bytes_per_channel;
-    int linesize;
-    GetByteContext g;
-} SgiState;
-
 /**
  * Expand an RLE row into a channel.
- * @param s the current image state
+ * @param logctx a logcontext
  * @param out_buf Points to one line after the output buffer.
+ * @param g   GetByteContext used to read input from
  * @param len length of out_buf in bytes
  * @param pixelstride pixel stride of input buffer
  * @return size of output in bytes, else return error code.
  */
-static int expand_rle_row8(SgiState *s, uint8_t *out_buf,
+static int expand_rle_row8(void *logctx, uint8_t *out_buf,
+                           GetByteContext *g,
                            int len, int pixelstride)
 {
     unsigned char pixel, count;
@@ -51,26 +43,26 @@ static int expand_rle_row8(SgiState *s, uint8_t *out_buf,
     uint8_t *out_end = out_buf + len;
 
     while (out_buf < out_end) {
-        if (bytestream2_get_bytes_left(&s->g) < 1)
+        if (bytestream2_get_bytes_left(g) < 1)
             return AVERROR_INVALIDDATA;
-        pixel = bytestream2_get_byteu(&s->g);
+        pixel = bytestream2_get_byteu(g);
         if (!(count = (pixel & 0x7f))) {
             break;
         }
 
         /* Check for buffer overflow. */
         if (out_end - out_buf <= pixelstride * (count - 1)) {
-            av_log(s->avctx, AV_LOG_ERROR, "Invalid pixel count.\n");
+            av_log(logctx, AV_LOG_ERROR, "Invalid pixel count.\n");
             return AVERROR_INVALIDDATA;
         }
 
         if (pixel & 0x80) {
             while (count--) {
-                *out_buf = bytestream2_get_byte(&s->g);
+                *out_buf = bytestream2_get_byte(g);
                 out_buf += pixelstride;
             }
         } else {
-            pixel = bytestream2_get_byte(&s->g);
+            pixel = bytestream2_get_byte(g);
 
             while (count--) {
                 *out_buf = pixel;
@@ -81,7 +73,8 @@ static int expand_rle_row8(SgiState *s, uint8_t *out_buf,
     return (out_buf - orig) / pixelstride;
 }
 
-static int expand_rle_row16(SgiState *s, uint16_t *out_buf,
+static int expand_rle_row16(void *logctx, uint16_t *out_buf,
+                            GetByteContext *g,
                             int len, int pixelstride)
 {
     unsigned short pixel;
@@ -90,26 +83,26 @@ static int expand_rle_row16(SgiState *s, uint16_t *out_buf,
     uint16_t *out_end = out_buf + len;
 
     while (out_buf < out_end) {
-        if (bytestream2_get_bytes_left(&s->g) < 2)
+        if (bytestream2_get_bytes_left(g) < 2)
             return AVERROR_INVALIDDATA;
-        pixel = bytestream2_get_be16u(&s->g);
+        pixel = bytestream2_get_be16u(g);
         if (!(count = (pixel & 0x7f)))
             break;
 
         /* Check for buffer overflow. */
         if (out_end - out_buf <= pixelstride * (count - 1)) {
-            av_log(s->avctx, AV_LOG_ERROR, "Invalid pixel count.\n");
+            av_log(logctx, AV_LOG_ERROR, "Invalid pixel count.\n");
             return AVERROR_INVALIDDATA;
         }
 
         if (pixel & 0x80) {
             while (count--) {
-                pixel = bytestream2_get_ne16(&s->g);
+                pixel = bytestream2_get_ne16(g);
                 AV_WN16A(out_buf, pixel);
                 out_buf += pixelstride;
             }
         } else {
-            pixel = bytestream2_get_ne16(&s->g);
+            pixel = bytestream2_get_ne16(g);
 
             while (count--) {
                 AV_WN16A(out_buf, pixel);
@@ -127,34 +120,38 @@ static int expand_rle_row16(SgiState *s, uint16_t *out_buf,
  * @param s the current image state
  * @return 0 if no error, else return error code.
  */
-static int read_rle_sgi(uint8_t *last_line, SgiState *s)
+static int read_rle_sgi(void *logctx, uint8_t *last_line, GetByteContext *g,
+                        ptrdiff_t stride, unsigned width, unsigned height,
+                        unsigned nb_components, unsigned bytes_per_channel)
 {
     uint8_t *dest_row;
-    unsigned int len = s->height * s->depth * 4;
-    GetByteContext g_table = s->g;
+    unsigned int len = height * nb_components * 4;
+    GetByteContext g_table = *g;
     unsigned int start_offset;
     int linesize, ret;
 
     /* size of  RLE offset and length tables */
-    if (len * 2 > bytestream2_get_bytes_left(&s->g)) {
+    if (len * 2 > bytestream2_get_bytes_left(g)) {
         return AVERROR_INVALIDDATA;
     }
 
-    for (unsigned z = 0; z < s->depth; z++) {
+    for (unsigned z = 0; z < nb_components; z++) {
         dest_row = last_line;
-        for (int remaining_lines = s->height;;) {
-            linesize = s->width * s->depth;
+        for (unsigned remaining_lines = height;;) {
+            linesize = width * nb_components;
             start_offset = bytestream2_get_be32(&g_table);
-            bytestream2_seek(&s->g, start_offset, SEEK_SET);
-            if (s->bytes_per_channel == 1)
-                ret = expand_rle_row8(s, dest_row + z, linesize, s->depth);
+            bytestream2_seek(g, start_offset, SEEK_SET);
+            if (bytes_per_channel == 1)
+                ret = expand_rle_row8(logctx, dest_row + z, g,
+                                      linesize, nb_components);
             else
-                ret = expand_rle_row16(s, (uint16_t *)dest_row + z, linesize, s->depth);
-            if (ret != s->width)
+                ret = expand_rle_row16(logctx, (uint16_t *)dest_row + z, g,
+                                       linesize, nb_components);
+            if (ret != width)
                 return AVERROR_INVALIDDATA;
             if (--remaining_lines == 0)
                 break;
-            dest_row -= s->linesize;
+            dest_row -= stride;
         }
     }
     return 0;
@@ -166,33 +163,34 @@ static int read_rle_sgi(uint8_t *last_line, SgiState *s)
  * @param s the current image state
  * @return 0 if read success, else return error code.
  */
-static int read_uncompressed_sgi(unsigned char *out_buf, SgiState *s)
+static int read_uncompressed_sgi(unsigned char *out_buf, GetByteContext *g,
+                                 ptrdiff_t stride, unsigned width, unsigned height,
+                                 unsigned nb_components, unsigned bytes_per_channel)
 {
-    int x, y, z;
-    unsigned int offset = s->height * s->width * s->bytes_per_channel;
+    unsigned int offset = height * width * bytes_per_channel;
     GetByteContext gp[4];
     uint8_t *out_end;
 
     /* Test buffer size. */
-    if (offset * s->depth > bytestream2_get_bytes_left(&s->g))
+    if (offset * nb_components > bytestream2_get_bytes_left(g))
         return AVERROR_INVALIDDATA;
 
     /* Create a reader for each plane */
-    for (z = 0; z < s->depth; z++) {
-        gp[z] = s->g;
+    for (unsigned z = 0; z < nb_components; z++) {
+        gp[z] = *g;
         bytestream2_skip(&gp[z], z * offset);
     }
 
-    for (y = s->height - 1; y >= 0; y--) {
-        out_end = out_buf + (y * s->linesize);
-        if (s->bytes_per_channel == 1) {
-            for (x = s->width; x > 0; x--)
-                for (z = 0; z < s->depth; z++)
+    for (int y = height - 1; y >= 0; y--) {
+        out_end = out_buf + y * stride;
+        if (bytes_per_channel == 1) {
+            for (unsigned x = width; x > 0; x--)
+                for (unsigned z = 0; z < nb_components; z++)
                     *out_end++ = bytestream2_get_byteu(&gp[z]);
         } else {
             uint16_t *out16 = (uint16_t *)out_end;
-            for (x = s->width; x > 0; x--)
-                for (z = 0; z < s->depth; z++)
+            for (unsigned x = width; x > 0; x--)
+                for (unsigned z = 0; z < nb_components; z++)
                     *out16++ = bytestream2_get_ne16u(&gp[z]);
         }
     }
@@ -202,31 +200,32 @@ static int read_uncompressed_sgi(unsigned char *out_buf, SgiState *s)
 static int decode_frame(AVCodecContext *avctx, AVFrame *p,
                         int *got_frame, AVPacket *avpkt)
 {
-    SgiState *s = avctx->priv_data;
-    unsigned int dimension, rle;
+    GetByteContext g;
+    unsigned int bytes_per_channel, nb_components, dimension, rle, width;
+    int height;
     int ret = 0;
     uint8_t *out_buf, *last_line;
 
-    bytestream2_init(&s->g, avpkt->data, avpkt->size);
-    if (bytestream2_get_bytes_left(&s->g) < SGI_HEADER_SIZE) {
+    bytestream2_init(&g, avpkt->data, avpkt->size);
+    if (bytestream2_get_bytes_left(&g) < SGI_HEADER_SIZE) {
         av_log(avctx, AV_LOG_ERROR, "buf_size too small (%d)\n", avpkt->size);
         return AVERROR_INVALIDDATA;
     }
 
     /* Test for SGI magic. */
-    if (bytestream2_get_be16u(&s->g) != SGI_MAGIC) {
+    if (bytestream2_get_be16u(&g) != SGI_MAGIC) {
         av_log(avctx, AV_LOG_ERROR, "bad magic number\n");
         return AVERROR_INVALIDDATA;
     }
 
-    rle                  = bytestream2_get_byteu(&s->g);
-    s->bytes_per_channel = bytestream2_get_byteu(&s->g);
-    dimension            = bytestream2_get_be16u(&s->g);
-    s->width             = bytestream2_get_be16u(&s->g);
-    s->height            = bytestream2_get_be16u(&s->g);
-    s->depth             = bytestream2_get_be16u(&s->g);
+    rle                  = bytestream2_get_byteu(&g);
+    bytes_per_channel    = bytestream2_get_byteu(&g);
+    dimension            = bytestream2_get_be16u(&g);
+    width                = bytestream2_get_be16u(&g);
+    height               = bytestream2_get_be16u(&g);
+    nb_components        = bytestream2_get_be16u(&g);
 
-    if (s->bytes_per_channel != 1 && s->bytes_per_channel != 2) {
+    if (bytes_per_channel != 1 && bytes_per_channel != 2) {
         av_log(avctx, AV_LOG_ERROR, "wrong channel number\n");
         return AVERROR_INVALIDDATA;
     }
@@ -237,18 +236,18 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *p,
         return AVERROR_INVALIDDATA;
     }
 
-    if (s->depth == SGI_GRAYSCALE) {
-        avctx->pix_fmt = s->bytes_per_channel == 2 ? AV_PIX_FMT_GRAY16BE : AV_PIX_FMT_GRAY8;
-    } else if (s->depth == SGI_RGB) {
-        avctx->pix_fmt = s->bytes_per_channel == 2 ? AV_PIX_FMT_RGB48BE : AV_PIX_FMT_RGB24;
-    } else if (s->depth == SGI_RGBA) {
-        avctx->pix_fmt = s->bytes_per_channel == 2 ? AV_PIX_FMT_RGBA64BE : AV_PIX_FMT_RGBA;
+    if (nb_components == SGI_GRAYSCALE) {
+        avctx->pix_fmt = bytes_per_channel == 2 ? AV_PIX_FMT_GRAY16BE : AV_PIX_FMT_GRAY8;
+    } else if (nb_components == SGI_RGB) {
+        avctx->pix_fmt = bytes_per_channel == 2 ? AV_PIX_FMT_RGB48BE : AV_PIX_FMT_RGB24;
+    } else if (nb_components == SGI_RGBA) {
+        avctx->pix_fmt = bytes_per_channel == 2 ? AV_PIX_FMT_RGBA64BE : AV_PIX_FMT_RGBA;
     } else {
         av_log(avctx, AV_LOG_ERROR, "wrong picture format\n");
         return AVERROR_INVALIDDATA;
     }
 
-    ret = ff_set_dimensions(avctx, s->width, s->height);
+    ret = ff_set_dimensions(avctx, width, height);
     if (ret < 0)
         return ret;
 
@@ -259,16 +258,16 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *p,
     p->key_frame = 1;
     out_buf = p->data[0];
 
-    last_line = out_buf + p->linesize[0] * (s->height - 1);
-
-    s->linesize = p->linesize[0];
+    last_line = out_buf + p->linesize[0] * (height - 1);
 
     /* Skip header. */
-    bytestream2_seek(&s->g, SGI_HEADER_SIZE, SEEK_SET);
+    bytestream2_seek(&g, SGI_HEADER_SIZE, SEEK_SET);
     if (rle) {
-        ret = read_rle_sgi(last_line, s);
+        ret = read_rle_sgi(avctx, last_line, &g, p->linesize[0],
+                           width, height, nb_components, bytes_per_channel);
     } else {
-        ret = read_uncompressed_sgi(out_buf, s);
+        ret = read_uncompressed_sgi(out_buf, &g, p->linesize[0],
+                                    width, height, nb_components, bytes_per_channel);
     }
     if (ret)
         return ret;
@@ -277,22 +276,11 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *p,
     return avpkt->size;
 }
 
-static av_cold int sgi_decode_init(AVCodecContext *avctx)
-{
-    SgiState *s = avctx->priv_data;
-
-    s->avctx = avctx;
-
-    return 0;
-}
-
 const FFCodec ff_sgi_decoder = {
     .p.name         = "sgi",
     CODEC_LONG_NAME("SGI image"),
     .p.type         = AVMEDIA_TYPE_VIDEO,
     .p.id           = AV_CODEC_ID_SGI,
-    .priv_data_size = sizeof(SgiState),
     FF_CODEC_DECODE_CB(decode_frame),
-    .init           = sgi_decode_init,
     .p.capabilities = AV_CODEC_CAP_DR1,
 };
-- 
2.34.1

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