添加一些关于midi播放的项目

Midi/music-box-nv32-master/WaveTableSynthesizer/PeriodTimer.s

@@ -0,0 +1,28 @@
+#include "Player.h"
+#include "RegDefNv32.h"
+
+#define PeriodTimerHandler PIT_Ch0Isr_Override
+
+.syntax unified
+.section .text
+.thumb_func
+.global PeriodTimerHandler
+.func PeriodTimerHandler
+PeriodTimerHandler:
+push {r4-r7,lr} // r0-r3,r12 saved by hardware when expection happening
+ldr r0,=#PIT_TFLG0
+ldr r1,[r0]
+ldr r2,=#PIT_TFLG_TIF_BIT
+orrs r1,r1,r2
+str r1,[r0]
+
+ldr r5,=#GlobalPlayerPtr
+ldr r5,[r5]
+ldr r6,=#pSynthesizer
+adds r0,r5,r6
+ldr r6,=#pScoreDecoder
+adds r1,r5,r6
+#include "Synth.inc"
+#include "UpdateTick.inc"
+pop {r4-r7,pc}
+.endfunc