All: Factorise CRC functions.

This saves 370 bytes of program space.

Cart_Reader/Cart_Reader.ino

@@ -531,32 +531,48 @@ static const uint32_t crc_32_tab[] PROGMEM = { /* CRC polynomial 0xedb88320 */
                                                0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
 };
 
-inline uint32_t updateCRC(uint8_t ch, uint32_t crc) {
+// Defined as a macros, as compiler disregards inlining requests and these are
-  uint32_t idx = ((crc) ^ (ch)) & 0xff;
+// performance-critical functions.
-  uint32_t tab_value = pgm_read_dword(crc_32_tab + idx);
+#define UPDATE_CRC(crc, ch) do { \
-  return tab_value ^ ((crc) >> 8);
+  uint8_t idx = ((crc) ^ (ch)) & 0xff; \
+  uint32_t tab_value = pgm_read_dword(crc_32_tab + idx); \
+  (crc) = tab_value ^ ((crc) >> 8); \
+} while (0)
+
+uint32_t updateCRC(const byte *buffer, size_t length, uint32_t crc) {
+  for (size_t c = 0; c < length; c++) {
+    UPDATE_CRC(crc, buffer[c]);
+  }
+  return crc;
+}
+
+uint32_t calculateCRC(const byte *buffer, size_t length) {
+  uint32_t crc = 0xFFFFFFFF;
+  updateCRC(buffer, length, crc);
+  return ~crc;
+}
+
+uint32_t calculateCRC(FsFile &infile) {
+  uint32_t byte_count;
+  uint32_t crc = 0xFFFFFFFF;
+
+  while((byte_count = infile.read(sdBuffer, sizeof(sdBuffer))) != 0) {
+    updateCRC(sdBuffer, byte_count, crc);
+  }
+  return ~crc;
 }
 
 // Calculate rom's CRC32 from SD
 uint32_t calculateCRC(char* fileName, char* folder, int offset) {
-  // Open folder
+  FsFile infile;
+  uint32_t result;
+
   sd.chdir(folder);
-  // Open file
+  if (infile.open(fileName, O_READ)) {
-  if (myFile.open(fileName, O_READ)) {
+    infile.seek(offset);
-    uint32_t oldcrc32 = 0xFFFFFFFF;
+    result = calculateCRC(infile);
-
+    infile.close();
-    // Skip iNES header
+    return result;
-    myFile.seek(offset);
-
-    for (unsigned long currByte = 0; currByte < ((myFile.fileSize() - offset) / 512); currByte++) {
-      myFile.read(sdBuffer, 512);
-      for (int c = 0; c < 512; c++) {
-        oldcrc32 = updateCRC(sdBuffer[c], oldcrc32);
-      }
-    }
-    // Close the file:
-    myFile.close();
-    return ~oldcrc32;
   } else {
     display_Clear();
     print_Msg(F("File "));

Cart_Reader/N64.ino

@@ -3379,8 +3379,6 @@ redumpsamefolder:
 
   // prepare crc32
   uint32_t oldcrc32 = 0xFFFFFFFF;
-  uint32_t tab_value = 0;
-  uint8_t idx = 0;
 
   // run combined dumper + crc32 routine for better performance, as N64 ROMs are quite large for an 8bit micro
   // currently dumps + checksums a 32MB cart in 170 seconds (down from 347 seconds)
@@ -3412,12 +3410,8 @@ redumpsamefolder:
       PORTH |= (1 << 6);
 
       // crc32 update
-      idx = ((oldcrc32) ^ (buffer[c]));
+      UPDATE_CRC(oldcrc32, buffer[c]);
-      tab_value = pgm_read_dword(crc_32_tab + idx);
+      UPDATE_CRC(oldcrc32, buffer[c + 1]);
-      oldcrc32 = tab_value ^ ((oldcrc32) >> 8);
-      idx = ((oldcrc32) ^ (buffer[c + 1]));
-      tab_value = pgm_read_dword(crc_32_tab + idx);
-      oldcrc32 = tab_value ^ ((oldcrc32) >> 8);
     }
 
     // Set the address for the next 512 bytes to dump
@@ -3443,12 +3437,8 @@ redumpsamefolder:
       PORTH |= (1 << 6);
 
       // crc32 update
-      idx = ((oldcrc32) ^ (buffer[c])) & 0xff;
+      UPDATE_CRC(oldcrc32, buffer[c]);
-      tab_value = pgm_read_dword(crc_32_tab + idx);
+      UPDATE_CRC(oldcrc32, buffer[c + 1]);
-      oldcrc32 = tab_value ^ ((oldcrc32) >> 8);
-      idx = ((oldcrc32) ^ (buffer[c + 1])) & 0xff;
-      tab_value = pgm_read_dword(crc_32_tab + idx);
-      oldcrc32 = tab_value ^ ((oldcrc32) >> 8);
     }
 
     processedProgressBar += 1024;

Cart_Reader/NES.ino

@@ -532,8 +532,8 @@ void getMapping() {
   // Read first 512 bytes of first and last block of PRG ROM and compute CRC32
   // MMC3 maps the last 8KB block of PRG ROM to 0xE000 while 0x8000 can contain random data after bootup
   for (int c = 0; c < 512; c++) {
-    oldcrc32 = updateCRC(read_prg_byte(0x8000 + c), oldcrc32);
+    UPDATE_CRC(oldcrc32, read_prg_byte(0x8000 + c));
-    oldcrc32MMC3 = updateCRC(read_prg_byte(0xE000 + c), oldcrc32MMC3);
+    UPDATE_CRC(oldcrc32MMC3, read_prg_byte(0xE000 + c));
   }
   oldcrc32 = ~oldcrc32;
   oldcrc32MMC3 = ~oldcrc32MMC3;
@@ -1054,27 +1054,19 @@ int int_pow(int base, int exp) {  // Power for int
    CRC Functions
  *****************************************/
 
-void calcCRC(char* checkFile, uint32_t* crcCopy, unsigned long offset) {
+void printCRC(char* checkFile, uint32_t* crcCopy, unsigned long offset) {
-  uint32_t crc = 0xFFFFFFFF;
+  uint32_t crc;
   char tempCRC[9];
-  int byte_count;
   FsFile crcFile = sd.open(checkFile);
+
   crcFile.seek(offset);
-  while (crcFile.available()) {
+  crc = calculateCRC(crcFile);
-    byte_count = crcFile.read(sdBuffer, sizeof(sdBuffer));
-    for (int x = 0; x < byte_count; x++) {
-      uint8_t c = sdBuffer[x];
-      crc = updateCRC(c, crc);
-    }
-  }
-  crc = ~crc;
   crcFile.close();
-  sprintf(tempCRC, "%08lX", crc);
 
   if (crcCopy != NULL) {
     *crcCopy = crc;
   }
-
+  sprintf(tempCRC, "%08lX", crc);
   print_Msg(F("CRC: "));
   println_Msg(tempCRC);
   display_Update();
@@ -1324,7 +1316,7 @@ void outputNES() {
   println_Msg(F(""));
   display_Update();
 
-  calcCRC(outputFile, NULL, crcOffset);
+  printCRC(outputFile, NULL, crcOffset);
   LED_RED_OFF;
   LED_GREEN_OFF;
   LED_BLUE_OFF;
@@ -3247,7 +3239,7 @@ void readPRG(boolean readrom) {
       println_Msg(F(""));
       display_Update();
 #ifndef nointro
-      calcCRC(fileName, &prg_crc32, 0);
+      printCRC(fileName, &prg_crc32, 0);
 #endif
     }
   }
@@ -3972,7 +3964,7 @@ void readCHR(boolean readrom) {
         println_Msg(F(""));
         display_Update();
 #ifndef nointro
-        calcCRC(fileName, &chr_crc32, 0);
+        printCRC(fileName, &chr_crc32, 0);
 #endif
       }
     }
@@ -4161,9 +4153,9 @@ void readRAM() {
       display_Update();
 
       if ((mapper == 16) || (mapper == 159))
-        calcCRC(fileName, NULL, 0);
+        printCRC(fileName, NULL, 0);
       else
-        calcCRC(fileName, NULL, 0);
+        printCRC(fileName, NULL, 0);
     }
   }
   set_address(0);

Cart_Reader/SFM.ino

@@ -807,12 +807,8 @@ boolean checkcart_SFM() {
   }
 
   // Calculate CRC32 of header
-  uint32_t oldcrc32 = 0xFFFFFFFF;
-  for (int c = 0; c < 80; c++) {
-    oldcrc32 = updateCRC(snesHeader[c], oldcrc32);
-  }
   char crcStr[9];
-  sprintf(crcStr, "%08lX", ~oldcrc32);
+  sprintf(crcStr, "%08lX", calculateCRC(snesHeader, 80));
 
   // Get Checksum as string
   sprintf(checksumStr, "%02X%02X", readBank_SFM(0, 65503), readBank_SFM(0, 65502));

Cart_Reader/SNES.ino

@@ -950,12 +950,8 @@ boolean checkcart_SNES() {
   }
 
   // Calculate CRC32 of header
-  uint32_t oldcrc32 = 0xFFFFFFFF;
-  for (int c = 0; c < 80; c++) {
-    oldcrc32 = updateCRC(snesHeader[c], oldcrc32);
-  }
   char crcStr[9];
-  sprintf(crcStr, "%08lX", ~oldcrc32);
+  sprintf(crcStr, "%08lX", calculateCRC(snesHeader, 80));
 
   // Get Checksum as string
   sprintf(checksumStr, "%02X%02X", snesHeader[0xFFDF - headerStart], snesHeader[0xFFDE - headerStart]);