Prepare to add hasSamplePtrHeader and hasSampleInstHeader in dispatch (WIP)

for refresh sample memory when loop/end pointer and instrument parameter changed. Also, this PR has minor code style fixes and add warning in MultiPCM sample map usage.

src/engine/platform/abstract.cpp

@@ -213,6 +213,14 @@ size_t DivDispatch::getSampleMemUsage(int index) {
   return 0;
 }
 
+bool DivDispatch::hasSamplePtrHeader(int index) {
+  return false;
+}
+
+bool DivDispatch::hasSampleInstHeader(int index) {
+  return false;
+}
+
 const DivMemoryComposition* DivDispatch::getMemCompo(int index) {
   return NULL;
 }

src/engine/platform/opl.cpp

@@ -3244,6 +3244,14 @@ size_t DivPlatformOPL::getSampleMemUsage(int index) {
           (index==0 && adpcmChan>=0)?adpcmBMemLen:0;
 }
 
+bool DivPlatformOPL::hasSamplePtrHeader(int index) {
+  return (index==0 && pcmChanOffs>=0);
+}
+
+bool DivPlatformOPL::hasSampleInstHeader(int index) {
+  return (index==0 && pcmChanOffs>=0);
+}
+
 bool DivPlatformOPL::isSampleLoaded(int index, int sample) {
   if (index!=0) return false;
   if (sample<0 || sample>32767) return false;

src/engine/platform/opl.h

@@ -218,6 +218,8 @@ class DivPlatformOPL: public DivDispatch {
     const void* getSampleMem(int index);
     size_t getSampleMemCapacity(int index);
     size_t getSampleMemUsage(int index);
+    bool hasSamplePtrHeader(int index=0);
+    bool hasSampleInstHeader(int index=0);
     bool isSampleLoaded(int index, int sample);
     const DivMemoryComposition* getMemCompo(int index);
     void renderSamples(int chipID);

src/engine/platform/snes.cpp

@@ -964,6 +964,10 @@ size_t DivPlatformSNES::getSampleMemUsage(int index) {
   return index == 0 ? sampleMemLen : 0;
 }
 
+bool DivPlatformSNES::hasSamplePtrHeader(int index) {
+  return true;
+}
+
 bool DivPlatformSNES::isSampleLoaded(int index, int sample) {
   if (index!=0) return false;
   if (sample<0 || sample>32767) return false;

src/engine/platform/snes.h

@@ -124,9 +124,10 @@ class DivPlatformSNES: public DivDispatch {
     void poke(unsigned int addr, unsigned short val);
     void poke(std::vector<DivRegWrite>& wlist);
     const char** getRegisterSheet();
-    const void* getSampleMem(int index = 0);
-    size_t getSampleMemCapacity(int index = 0);
-    size_t getSampleMemUsage(int index = 0);
+    const void* getSampleMem(int index=0);
+    size_t getSampleMemCapacity(int index=0);
+    size_t getSampleMemUsage(int index=0);
+    bool hasSamplePtrHeader(int index=0);
     bool isSampleLoaded(int index, int sample);
     const DivMemoryComposition* getMemCompo(int index);
     void renderSamples(int chipID);