Function SPIEnableWriting

3ds/source/spi.cpp:84–114

}

Result SPIEnableWriting(CardType type)
{
    u8 cmd = SPI_CMD_WREN, statusReg = 0;
    Result res = SPIWriteRead(type, &cmd, 1, NULL, 0, 0, 0);
    int panic  = 0;

    if (res || type == EEPROM_512B)
        return res; // Weird, but works (otherwise we're getting an infinite loop for that chip type).
    cmd = SPI_CMD_RDSR;

    // Bail out after a bounded number of polls instead of spinning forever.
    // The actual precondition for a write is that the write-enable latch (WEL) is set. The 8MB
    // cart legitimately leaves block-protect/SRWD bits set in the status register even when armed for
    // writing (sr stays 0x86, and those bits cannot be cleared via WRSR — SRWD + WP# hardware-lock
    // them), so for it we only require WEL. Every other chip clears to a bare 0x02 after WREN, so the
    // stricter "nothing but WEL set" check is kept for them to preserve existing behaviour.
    do {
        res = SPIWriteRead(type, &cmd, 1, &statusReg, 1, 0, 0);
        if (res)
            return res;
        if (type == FLASH_8MB) {
            if (statusReg & SPI_FLG_WEL)
                break;
        }
        else if (!(statusReg & ~SPI_FLG_WEL)) {
            break;
        }
    } while (++panic < 1000);

    return panic >= 1000 ? 1 : 0;
}

Result SPIReadJEDECIDAndStatusReg(CardType type, u32* id, u8* statusReg)
{