Report replay frame number for active_replay stdout api (#17039)

This changes the replay movie's frame_ptr (a 20-bit number used to
point to a log of file offsets) into a frame counter, which is masked
against the 20-bit pattern for use in the file offset log but also
functions as a time index into the replay.  Right now that is reported
in `GET_CONFIG_PARAM active_replay` but in the future it could be used
to show how far into the replay we are during playback or how long the
replay is during recording.

command.c

@@ -408,12 +408,15 @@ bool command_get_config_param(command_t *cmd, const char* arg)
       input_driver_state_t *input_st = input_state_get_ptr();
       value            = value_dynamic;
       value_dynamic[0] = '\0';
-      if(input_st->bsv_movie_state_handle)
-         snprintf(value_dynamic, sizeof(value_dynamic), "%lld %u",
-               (long long)(input_st->bsv_movie_state_handle->identifier),
-               input_st->bsv_movie_state.flags);
+      if(input_st->bsv_movie_state_handle) {
+         bsv_movie_t *movie = input_st->bsv_movie_state_handle;
+         snprintf(value_dynamic, sizeof(value_dynamic), "%lld %u %lld",
+               (long long)(movie->identifier),
+                  input_st->bsv_movie_state.flags,
+                  (long long)(movie->frame_counter));
+      }
       else
-         strlcpy(value_dynamic, "0 0", sizeof(value_dynamic));
+         strlcpy(value_dynamic, "0 0 0", sizeof(value_dynamic));
    }
    #endif
    /* TODO: query any string */

input/input_driver.c

@@ -5685,11 +5685,11 @@ void bsv_movie_frame_rewind(void)
 
    handle->did_rewind = true;
 
-   if (     (handle->frame_ptr <= 1)
+   if (     ( (handle->frame_counter & handle->frame_mask) <= 1)
          && (handle->frame_pos[0] == handle->min_file_pos))
    {
       /* If we're at the beginning... */
-      handle->frame_ptr = 0;
+      handle->frame_counter = 0;
       intfstream_seek(handle->file, (int)handle->min_file_pos, SEEK_SET);
       if (recording)
          intfstream_truncate(handle->file, (int)handle->min_file_pos);
@@ -5702,11 +5702,14 @@ void bsv_movie_frame_rewind(void)
        *
        * Sucessively rewinding frames, we need to rewind past the read data,
        * plus another. */
-      handle->frame_ptr = (handle->frame_ptr -
-            (handle->first_rewind ? 1 : 2)) & handle->frame_mask;
-      intfstream_seek(handle->file, (int)handle->frame_pos[handle->frame_ptr], SEEK_SET);
+      uint8_t delta = handle->first_rewind ? 1 : 2;
+      if (handle->frame_counter >= delta)
+         handle->frame_counter -= delta;
+      else
+         handle->frame_counter = 0;
+      intfstream_seek(handle->file, (int)handle->frame_pos[handle->frame_counter & handle->frame_mask], SEEK_SET);
       if (recording)
-         intfstream_truncate(handle->file, (int)handle->frame_pos[handle->frame_ptr]);
+         intfstream_truncate(handle->file, (int)handle->frame_pos[handle->frame_counter & handle->frame_mask]);
    }
 
    if (intfstream_tell(handle->file) <= (long)handle->min_file_pos)
@@ -5758,7 +5761,7 @@ void bsv_movie_finish_rewind(input_driver_state_t *input_st)
    bsv_movie_t *handle  = input_st->bsv_movie_state_handle;
    if (!handle)
       return;
-   handle->frame_ptr    = (handle->frame_ptr + 1) & handle->frame_mask;
+   handle->frame_counter += 1;
    handle->first_rewind = !handle->did_rewind;
    handle->did_rewind   = false;
 }
@@ -5797,7 +5800,7 @@ void bsv_movie_next_frame(input_driver_state_t *input_st)
       bsv_movie_handle_clear_key_events(handle);
 
       /* Maybe record checkpoint */
-      if (checkpoint_interval != 0 && handle->frame_ptr > 0 && (handle->frame_ptr % (checkpoint_interval*60) == 0))
+      if (checkpoint_interval != 0 && handle->frame_counter > 0 && (handle->frame_counter % (checkpoint_interval*60) == 0))
       {
          retro_ctx_serialize_info_t serial_info;
          uint8_t frame_tok = REPLAY_TOKEN_CHECKPOINT_FRAME;
@@ -5893,7 +5896,7 @@ void bsv_movie_next_frame(input_driver_state_t *input_st)
         }
       }
    }
-   handle->frame_pos[handle->frame_ptr] = intfstream_tell(handle->file);
+   handle->frame_pos[handle->frame_counter & handle->frame_mask] = intfstream_tell(handle->file);
 }
 
 size_t replay_get_serialize_size(void)

input/input_driver.h

@@ -201,7 +201,7 @@ struct bsv_movie
    size_t *frame_pos;
    int64_t identifier;
    size_t frame_mask;
-   size_t frame_ptr;
+   uint64_t frame_counter;
    size_t min_file_pos;
    size_t state_size;
    bsv_key_data_t key_events[NAME_MAX_LENGTH]; /* uint32_t alignment */