From 4ee17d35cdfce8661286d97b8f3c7b0615c0d66f Mon Sep 17 00:00:00 2001
From: tildearrow <tildearrow@protonmail.com>
Date: Thu, 20 Jan 2022 02:46:28 -0500
Subject: [PATCH] implement sample loop on the rest of systems

---
 src/engine/platform/arcade.cpp  | 14 ++++++++++++--
 src/engine/platform/genesis.cpp |  6 +++++-
 src/engine/platform/nes.cpp     |  6 +++++-
 src/engine/platform/pce.cpp     |  6 +++++-
 4 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/src/engine/platform/arcade.cpp b/src/engine/platform/arcade.cpp
index ec3e0ac2f..e9d9b6505 100644
--- a/src/engine/platform/arcade.cpp
+++ b/src/engine/platform/arcade.cpp
@@ -70,7 +70,12 @@ void DivPlatformArcade::acquire_nuked(short* bufL, short* bufR, size_t start, si
           }
           chan[i].pcm.pos+=chan[i].pcm.freq;
           if (chan[i].pcm.pos>=(s->rendLength<<8)) {
-            chan[i].pcm.sample=-1;
+            if (s->loopStart>=0 && s->loopStart<=(int)s->rendLength) {
+              // Sega PCM limitation
+              chan[i].pcm.pos=(s->loopStart&(~0xff))<<8;
+            } else {
+              chan[i].pcm.sample=-1;
+            }
           }
         }
       }
@@ -127,7 +132,12 @@ void DivPlatformArcade::acquire_ymfm(short* bufL, short* bufR, size_t start, siz
           }
           chan[i].pcm.pos+=chan[i].pcm.freq;
           if (chan[i].pcm.pos>=(s->rendLength<<8)) {
-            chan[i].pcm.sample=-1;
+            if (s->loopStart>=0 && s->loopStart<=(int)s->rendLength) {
+              // Sega PCM limitation
+              chan[i].pcm.pos=(s->loopStart&(~0xff))<<8;
+            } else {
+              chan[i].pcm.sample=-1;
+            }
           }
         }
       }
diff --git a/src/engine/platform/genesis.cpp b/src/engine/platform/genesis.cpp
index c341de955..d59260f1d 100644
--- a/src/engine/platform/genesis.cpp
+++ b/src/engine/platform/genesis.cpp
@@ -26,7 +26,11 @@ void DivPlatformGenesis::acquire(short* bufL, short* bufR, size_t start, size_t
           }
         }
         if (dacPos>=s->rendLength) {
-          dacSample=-1;
+          if (s->loopStart>=0 && s->loopStart<=(int)s->rendLength) {
+            dacPos=s->loopStart;
+          } else {
+            dacSample=-1;
+          }
         }
         dacPeriod+=dacRate;
       }
diff --git a/src/engine/platform/nes.cpp b/src/engine/platform/nes.cpp
index 48157df56..50c81fa0a 100644
--- a/src/engine/platform/nes.cpp
+++ b/src/engine/platform/nes.cpp
@@ -23,7 +23,11 @@ void DivPlatformNES::acquire(short* bufL, short* bufR, size_t start, size_t len)
           }
         }
         if (dacPos>=s->rendLength) {
-          dacSample=-1;
+          if (s->loopStart>=0 && s->loopStart<=(int)s->rendLength) {
+            dacPos=s->loopStart;
+          } else {
+            dacSample=-1;
+          }
         }
         dacPeriod-=rate;
       }
diff --git a/src/engine/platform/pce.cpp b/src/engine/platform/pce.cpp
index cc6121368..e2719905f 100644
--- a/src/engine/platform/pce.cpp
+++ b/src/engine/platform/pce.cpp
@@ -32,7 +32,11 @@ void DivPlatformPCE::acquire(short* bufL, short* bufR, size_t start, size_t len)
             chWrite(i,0x06,(((unsigned short)s->rendData[chan[i].dacPos++]+0x8000)>>11));
           }
           if (chan[i].dacPos>=s->rendLength) {
-            chan[i].dacSample=-1;
+            if (s->loopStart>=0 && s->loopStart<=(int)s->rendLength) {
+              chan[i].dacPos=s->loopStart;
+            } else {
+              chan[i].dacSample=-1;
+            }
           }
           chan[i].dacPeriod+=chan[i].dacRate;
         }