feat(flash): Show sector role during CRC checking

This matches the NOR flash partition table in https://github.com/mindboards/ev3sources/blob/78ebaf5b6f8fe31cc17aa5dce0f8e4916a4fc072/extra/linux-03.20.00.13/arch/arm/mach-davinci/board-da850-evm.c#L245
and the scripts in the firmware.

Author: JakubVanek

src/bl_install.c

@@ -47,6 +47,20 @@ static int bootloader_send(FILE *fp, int length, u32* pCrc32);
  */
 static int bootloader_checksum(int offset, int length, u32 *pCrc32);
 
+/**
+ * @brief Describe the role of the current sector
+ * @param Sector number
+ * @retval String describing the role of the sector
+ */
+static const char *sector_explanation(u32 sector_number);
+
+/**
+ * @brief Check whether the given sector is modified by the brick itself
+ * @param Sector number
+ * @retval True if the sector CRC can change, false otherwise
+ */
+static bool sector_is_mutable(u32 sector_number);
+
 /**
  * @brief Install new firmware binary to the internal flash.
  * @param fp Firmware file to download to the brick.
@@ -258,6 +272,8 @@ int bootloader_crc(FILE *fp, u32 starting_sector, u32 num_sectors, bool verbose)
 		// Compares the remote and local CRCs of each sector, showing the results of each.
 		printf("Sector CRC comparison:\n");
 		bool all_ok = true;
+		const char *last_area = NULL;
+
 		for (u32 sector = starting_sector; sector < starting_sector + num_sectors; sector++) {
 			u32 local_sector_crc32 = crc32(0, firmware + sector * FLASH_SECTOR_SIZE, FLASH_SECTOR_SIZE);
 			u32 remote_sector_crc32 = 0;
@@ -266,6 +282,12 @@ int bootloader_crc(FILE *fp, u32 starting_sector, u32 num_sectors, bool verbose)
 			bool this_ok = remote_sector_crc32 == local_sector_crc32;
 			all_ok = all_ok && this_ok;
 
+			const char *area = sector_explanation(sector);
+			if (area != last_area) { // static string literals can be compared by pointers
+				printf("* %s%s\n", area, sector_is_mutable(sector) ? "; CRC mismatch is expected here" : "");
+				last_area = area;
+			}
+
 			if (sector_err == ERR_UNK) {
 				printf("Sector %3d: Remote CRC = %08X, local CRC = %08X%s\n", sector, remote_sector_crc32,
 					local_sector_crc32, this_ok ? "" : " ERR");
@@ -298,6 +320,36 @@ int bootloader_crc(FILE *fp, u32 starting_sector, u32 num_sectors, bool verbose)
 	return err;
 }
 
+static const char *sector_explanation(u32 sector_number)
+{
+	const char *explanation = "unknown";
+	if (sector_number < 0x04) { // 0x000000 - 0x03FFFF
+		explanation = "U-Boot";
+	} else if (sector_number == 0x04) { // 0x040000 - 0x04FFFF
+		explanation = "U-Boot environment";
+	} else if (sector_number < 0x25) { // 0x050000 - 0x24FFFF
+		explanation = "Linux kernel";
+	} else if (sector_number < 0xCB) { // 0x250000 - 0xCAFFFF
+		explanation = "Root file system";
+	} else if (sector_number < 0xFA) { // 0xCB0000 - 0xF9FFFF
+		explanation = "User data";
+	}
+	return explanation;
+}
+
+static bool sector_is_mutable(u32 sector_number)
+{
+	bool mutable = false;
+	if (sector_number == 4) {
+		// U-Boot environment
+		mutable = true;
+	} else if (sector_number >= 0xCB) {
+		// User data
+		mutable = true;
+	}
+	return mutable;
+}
+
 static int bootloader_checksum(int offset, int length, u32 *pCrc32)
 {
 	*pCrc32 = 0;