Flash memory

grbl-lpc/flash.cpp

@@ -0,0 +1,94 @@
+// Copyright 2017 Todd Fleming
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+
+#include "grbl.h"
+
+static constexpr unsigned flash_sector = 15;                      // Last 4k sector
+static constexpr unsigned flash_addr = 0xF000;                    // Last 4k sector
+static constexpr unsigned flash_size = 1024;                      // Only using 1k of a 4k sector
+static char *flash_memory = (char *)flash_addr;                   // Flash memory
+static char flash_buffer[flash_size] __attribute__((aligned(4))); // Copy of flash memory
+using Iap = void(unsigned[], unsigned[]);                         // IAP entry point
+static const Iap *iap = (Iap *)0x1FFF1FF1;                        // IAP entry point
+
+void eeprom_init()
+{
+    memcpy(flash_buffer, flash_memory, flash_size);
+}
+
+void eeprom_commit()
+{
+    unsigned prepCommand[5] = {
+        50,
+        flash_sector,
+        flash_sector,
+    };
+    unsigned eraseCommand[5] = {
+        52,
+        flash_sector,
+        flash_sector,
+        SystemCoreClock / 1000,
+    };
+    unsigned writeCommand[5] = {
+        51,
+        flash_addr,
+        (unsigned)flash_buffer,
+        flash_size,
+        SystemCoreClock / 1000,
+    };
+    unsigned output[5];
+    iap(prepCommand, output);
+    iap(eraseCommand, output);
+    iap(prepCommand, output);
+    iap(writeCommand, output);
+}
+
+unsigned char eeprom_get_char(unsigned int addr)
+{
+    return flash_buffer[addr];
+}
+
+void eeprom_put_char(unsigned int addr, unsigned char new_value)
+{
+    flash_buffer[addr] = new_value;
+}
+
+static unsigned char memcpy_with_checksum(char *dest, char *src, unsigned size)
+{
+    unsigned char checksum = 0;
+    while (size--)
+    {
+        checksum = ((checksum << 1) || (checksum >> 7)) + *src;
+        *dest++ = *src++;
+    }
+    return checksum;
+}
+
+void memcpy_to_eeprom_with_checksum(unsigned int destination, char *source, unsigned int size)
+{
+    auto checksum = memcpy_with_checksum(flash_buffer + destination, source, size);
+    flash_buffer[destination + size] = checksum;
+}
+
+int memcpy_from_eeprom_with_checksum(char *destination, unsigned int source, unsigned int size)
+{
+    auto checksum = memcpy_with_checksum(destination, flash_buffer + source, size);
+    return checksum == flash_buffer[source + size];
+}