added DMA double buffering for consideration

Author: rikkuness

libs/graphics/lcd_fsmc.c

@@ -560,7 +560,9 @@ void LCD_init_hardware() {
 
 #ifdef LCD_TEARING
   jshPinSetState(LCD_TEARING, JSHPINSTATE_GPIO_IN_PULLDOWN);
-#endif
+  #endif
+
+  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2, ENABLE);
 }
 
 #endif // NOT ILI9325_BITBANG
@@ -1917,12 +1919,41 @@ void lcdFSMC_blitStart(JsGraphics *gfx, int x, int y, int w, int h) {
   // Wait for the ILI9488 Tearing Effect signal to indicate start of V-blank.
   // TE pin is push-pull: HIGH during V-blank (500-2000us safe write window),
   // LOW during scan (10-40ms panel refresh from GRAM).
-  // 10ms delay to avoid tight hot loops eating power
-  while (!jshPinGetValue(LCD_TEARING)) jshDelayMicroseconds(10);
+  while (!jshPinGetValue(LCD_TEARING));
 #endif
   lcdSetWindow(gfx, x, y, x+w-1, y+h-1);
   lcdSetWrite();
 }
+
+void lcdFSMC_dmaStart(uint16_t *buf, int count) {
+  // disable stream and wait for disable before send
+  DMA2_Stream0->CR &= ~DMA_SxCR_EN; 
+  while (DMA2_Stream0->CR & DMA_SxCR_EN);
+  
+  // clear interrup and error flags
+  DMA2->LIFCR = DMA_LIFCR_CTCIF0  |
+                DMA_LIFCR_CHTIF0  |
+                DMA_LIFCR_CTEIF0  |
+                DMA_LIFCR_CDMEIF0 |
+                DMA_LIFCR_CFEIF0;  
+
+  DMA2_Stream0->PAR  = (uint32_t)buf;
+  DMA2_Stream0->M0AR = (uint32_t)&LCD_RAM;
+  DMA2_Stream0->NDTR = (uint16_t)count;
+  DMA2_Stream0->FCR  = 0; // direct mode
+
+  DMA2_Stream0->CR = DMA_SxCR_DIR_1   | // mem-to-mem mode
+                     DMA_SxCR_PINC    | // increment pointer (buf++)
+                     DMA_SxCR_PSIZE_0 | // src size: 16-bit (half-word)
+                     DMA_SxCR_MSIZE_0 | // dest size: 16-bit (half-word)
+                     DMA_SxCR_EN;       // enable stream
+}
+
+void lcdFSMC_dmaWait(void) {
+  while (DMA2_Stream0->NDTR);
+  DMA2_Stream0->CR &= ~1U;
+}
+
 void lcdFSMC_setCursor(JsGraphics *gfx, int x, int y) {
   lcdSetCursor(gfx,x,y);
   //lcdSetWindow(gfx,x,y,gfx->data.width-1,y);

libs/graphics/lcd_fsmc.h

@@ -22,6 +22,8 @@ void lcdFSMC_blitStart(JsGraphics *gfx, int x, int y, int w, int h);
 void lcdFSMC_setCursor(JsGraphics *gfx, int x, int y);
 void lcdFSMC_blitPixel(unsigned int col);
 void lcdFSMC_blitEnd();
+void lcdFSMC_dmaStart(uint16_t *buf, int count);
+void lcdFSMC_dmaWait(void);
 
 void lcdFSMC_setPower(bool isOn);
 

libs/pipboy/jswrap_pipboy.c

@@ -83,6 +83,8 @@ bool audioRepeats; // should this stream repeat?
 
 JsSysTime videoFrameTime;
 JsSysTime videoNextFrameTime;
+static uint16_t blitRowA[480];
+static uint16_t blitRowB[480];
 bool debugInfo = false;
 int startX=0;
 int startY=0;
@@ -2025,6 +2027,8 @@ void jswrap_pb_blitScreen(JsVar *image, JsVar *options) {
   yoffset += 320; // to avoid negative values
   lcdFSMC_blitStart(gfx, 0,y1, 480,y2+1-y1);
   for (int y=y1;y<=y2;y++) {
+    uint16_t *rowBuf = (y & 1) ? blitRowB : blitRowA; // double buffer selection
+
     // work out row pointers
     row1 = &imgPtr[((y+yoffset-ydiff)%320)*120]; // 480 pixels, 2bpp = 120 bytes per row
     row2 = &imgPtr[((y+yoffset)%320)*120]; // 480 pixels, 2bpp = 120 bytes per row
@@ -2033,19 +2037,20 @@ void jswrap_pb_blitScreen(JsVar *image, JsVar *options) {
 
     uint32_t pixels = 0;
     uint8_t pixelUp, pixelDn;
+    int p = 0; // index into DMA row buffer
+    #define BLITPIXEL \
+      filterResult32 = (pixels&mulx1) + ((pixels&mulx2)<<1); /* Apply 8x 2bit filter */ \
+      filterResult32 = (filterResult32&0x0F0F0F0F) + ((filterResult32>>4)&0x0F0F0F0F) ; /* Merge each nibble, now we have 8 bits to play with */ \
+      filterResult32 = filterResult32 + (filterResult32>>8); \
+      filterResult32 = (filterResult32 + (filterResult32>>16)) & 255; \
+      filterResult32 = ((((pixelUp+pixelDn)<<1) + filterResult32)*3)>>3; /* blur upper and lower lines */ \
+      if (filterResult32>15) filterResult32=15; \
+      rowBuf[p++] = palette[filterResult32];
     for (int x=0;x<120;x++) {
       uint8_t p4up = *(row1++);
       uint8_t p4 = *(row2++);
       uint8_t p4dn = *(row3++);
       uint32_t filterResult32;
-      #define BLITPIXEL \
-        filterResult32 = (pixels&mulx1) + ((pixels&mulx2)<<1); /* Apply 8x 2bit filter */ \
-        filterResult32 = (filterResult32&0x0F0F0F0F) + ((filterResult32>>4)&0x0F0F0F0F) ; /* Merge each nibble, now we have 8 bits to play with */ \
-        filterResult32 = filterResult32 + (filterResult32>>8); \
-        filterResult32 = (filterResult32 + (filterResult32>>16)) & 255; \
-        filterResult32 = ((((pixelUp+pixelDn)<<1) + filterResult32)*3)>>3; /* blur upper and lower lines */ \
-        if (filterResult32>15) filterResult32=15; \
-        lcdFSMC_blitPixel(palette[filterResult32]);
       pixelUp = (p4up>>5);
       pixelDn = (p4dn>>5);
       pixels = (pixels<<4) | (p4>>6);
@@ -2064,7 +2069,10 @@ void jswrap_pb_blitScreen(JsVar *image, JsVar *options) {
       BLITPIXEL
       #undef BLITPIXEL
     }
+    if (y != y1) lcdFSMC_dmaWait();
+    lcdFSMC_dmaStart(rowBuf, 480);
   }
+  lcdFSMC_dmaWait();
   lcdFSMC_blitEnd();
   _jswrap_graphics_freeImageInfo(&img);
 }