From 9a2111f196121ff22ccb088e53522eab66f9ac4d Mon Sep 17 00:00:00 2001
From: Kevin Trogant <kevin@trogant.de>
Date: Tue, 17 Jan 2023 11:30:33 +0100
Subject: [PATCH] add untested playback api implementation

---
 rt_replay.h | 73 +++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 65 insertions(+), 8 deletions(-)

diff --git a/rt_replay.h b/rt_replay.h
index 6e977e9..06cb4eb 100644
--- a/rt_replay.h
+++ b/rt_replay.h
@@ -156,6 +156,7 @@ typedef struct
 typedef struct
 {
     rtr_record_frame* frame;
+    double timestamp;
     int is_finished;
 } rtr_playback_cursor;
 
@@ -177,17 +178,18 @@ int rtr_add_analog_event(rtr_recording* recording, rtr_uint32 axis, double value
  * Playback api
  */
 
-int rtr_open_recording(void* buffer, rtr_uint64 buffer_size, void* user_ctx, rtr_recording* recording);
+int rtr_open_recording(void* buffer, rtr_uint64 buffer_size, void* user_ctx, rtr_recording* recording, rtr_playback_cursor* cursor);
 
 void rtr_close_recording(rtr_recording* recording);
 
-void rtr_playback_frame(rtr_recording* recording, double delta);
+rtr_playback_cursor rtr_create_cursor(rtr_recording* recording);
 
-int rtr_get_events(rtr_recording* recording, unsigned int* num_events, rtr_event** events);
+void rtr_advance_playback(rtr_playback_cursor* cursor, double delta);
+
+int rtr_get_events(rtr_playback_cursor* cursor, unsigned int* num_events, rtr_event* events);
 
 #endif
 
-#define RT_REPLAY_IMPLEMENTATION
 #ifdef RT_REPLAY_IMPLEMENTATION
 #undef RT_REPLAY_IMPLEMENTATION
 
@@ -344,7 +346,7 @@ int rtr_add_analog_event(rtr_recording* recording, rtr_uint32 axis, double value
     return rtr_add_event(recording, event);
 }
 
-int rtr_open_recording(void* buffer, rtr_uint64 buffer_size, void* user_ctx, rtr_recording* recording)
+int rtr_open_recording(void* buffer, rtr_uint64 buffer_size, void* user_ctx, rtr_recording* recording, rtr_playback_cursor* cursor)
 {
     rtr_buffer_header* hdr = (rtr_buffer_header*)buffer;
     if (hdr->version != RTR_VERSION) {
@@ -376,6 +378,12 @@ int rtr_open_recording(void* buffer, rtr_uint64 buffer_size, void* user_ctx, rtr
     recording->timestamp     = 0.0;
     recording->ctx = user_ctx;
 
+    if (cursor) {
+        cursor->frame = recording->frames;
+        cursor->is_finished = 0;
+        cursor->timestamp   = 0.0;
+    }
+
     return RTR_SUCCESS;
 }
 
@@ -387,11 +395,60 @@ void rtr_close_recording(rtr_recording* recording)
     RTR_MEMSET(recording, 0, sizeof(recording));
 }
 
-void rtr_playback_frame(rtr_recording* recording, double delta)
+rtr_playback_cursor rtr_create_cursor(rtr_recording* recording)
 {
-    
+    rtr_playback_cursor cursor = {NULL, 0.0, 0};
+    if (recording->mode != RTR_RECORDING_MODE_PLAYBACK)
+        return cursor;
+    cursor.frame = recording->frames;
+    cursor.is_finished = 0;
+    cursor.timestamp   = 0.0;
+    return cursor;
 }
 
-int rtr_get_events(rtr_recording* recording, unsigned int* num_events, rtr_event** events);
+void rtr_advance_playback(rtr_playback_cursor* cursor, double delta)
+{
+    rtr_record_frame* next_frame = cursor->frame->next;
+    /* skip extended frames */
+    while (next_frame && next_frame->timestamp == cursor->frame->timestamp)
+        next_frame = next_frame->next;
+
+    if (next_frame) {
+        cursor->timestamp += delta;
+        if (cursor->timestamp >= next_frame->timestamp)
+            cursor->frame = next_frame;
+    }
+    else {
+        cursor->is_finished = 1;
+    }
+}
+
+int rtr_get_events(rtr_playback_cursor* cursor, unsigned int* num_events, rtr_event* events)
+{
+    /* its possible that multiple frames are concatenated together */
+    unsigned int n = (unsigned int)cursor->frame->num_events;
+
+    double ts = cursor->frame->timestamp;
+
+    rtr_record_frame* ext_frame = cursor->frame->next;
+    while (ext_frame->timestamp == ts) {
+        n += ext_frame->num_events;
+        ext_frame = ext_frame->next;
+    }
+
+    if (num_events)
+        *num_events = n;
+    if (events) {
+        RTR_MEMCPY(events, cursor->frame->events, cursor->frame->num_events * sizeof(rtr_event));
+        rtr_uint32 i = cursor->frame->num_events;
+        rtr_record_frame* ext_frame = cursor->frame->next;
+        while (ext_frame->timestamp == ts) {
+            RTR_MEMCPY(&events[i], ext_frame->events, ext_frame->num_events * sizeof(rtr_event));
+            i += ext_frame->num_events;
+            ext_frame = ext_frame->next;
+        }
+    }
+    return 1;
+}
 
 #endif