nuvoton ec crc calculator

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

#pragma pack(push)
#pragma pack(1)
struct HFCGP
{
    uint8_t CPRED:4;
    uint8_t FPRED:4;

};
struct header_data
{
    uint16_t signature;
    uint16_t reserved_0x02;
    uint8_t HCBAL_DAT;
    uint8_t HCBAH_DAT;
    uint16_t reserved_0x06;
    uint8_t HFCGML_DAT;
    uint8_t HFCGMH_DAT;
    uint8_t HFCGN_DAT;
    struct HFCGP HFCGP_DAT;
    uint16_t reserved_0x0c;
    uint8_t FL_SIZE_DAT;
    uint8_t BURST_DAT;
    uint8_t SPI_FL_DAT;
    uint8_t MISC_CTL;
    uint16_t reserved_0x12;
    uint32_t FIRMW_START;
    uint32_t FIRMW_SIZE;
    uint16_t reserved_0x1c[(0x40 - 0x1c)/2];
    uint16_t HEADER_CKSM;
    uint16_t reserved_0x42;
    uint32_t FIRMW_CKSM;
};
#pragma pack(pop)



void main(int argc,char ** argv)
{

    uint16_t csum=0;
    uint8_t buf[0x100];
    uint32_t csum2=0;
    size_t sz,k;
    uint8_t * buf2;

    if(argc!=2)
    {
        printf("usage:\n%s filename\n",argv[0]);
        exit(0);
    }
    FILE * fd=fopen(argv[1],"r+");
    if(!fd)
    {
        printf("failed to open a file %s\n",argv[1]);
        exit(1);
    }
    struct header_data *hd=(struct header_data *)&buf[0];
    sz=fread(buf,0x100,1,fd);
    if(sz!=1)
    {
        printf("failed to read a file %s\n",argv[1]);
        exit(1);
    }
    for(k=0;k<0x3f;k++)
        csum+=buf[k];
    printf("size=%ld\n\n",sizeof(struct header_data));

    printf(
        "signature=%04x\n"
        "reserved_0x02=%04x\n"
        "HCBAL_DAT=%02x\n"
        "HCBAH_DAT=%02x\n"
        "reserved_0x06=%04x\n"
        "HFCGML_DAT=%02x\n"
        "HFCGMH_DAT=%02x\n"
        "HFCGN_DAT=%02x\n"
        "HFCGP_DAT.CPRED=%02x\n"
        "HFCGP_DAT.FPRED=%02x\n"
        "reserved_0x0c=%04x\n"
        "FL_SIZE_DAT=%02x\n"
        "BURST_DAT=%02x\n"
        "SPI_FL_DAT=%02x\n"
        "MISC_CTL=%02x\n"
        "reserved_0x12=%04x\n"
        "FIRMW_START=%08x\n"
        "FIRMW_SIZE=%08x\n"
        "HEADER_CKSM=%04x\n"
        "reserved_0x42=%04x\n"
        "FIRMW_CKSM=%08x\n",
        (unsigned int)hd->signature,(unsigned int)hd->reserved_0x02,(unsigned int)hd->HCBAL_DAT,(unsigned int)hd->HCBAH_DAT,(unsigned int)hd->reserved_0x06,
        (unsigned int)hd->HFCGML_DAT,(unsigned int)hd->HFCGMH_DAT,(unsigned int)hd->HFCGN_DAT,(unsigned int)hd->HFCGP_DAT.CPRED,(unsigned int)hd->HFCGP_DAT.FPRED,
        (unsigned int)hd->reserved_0x0c,
        (unsigned int)hd->FL_SIZE_DAT,(unsigned int)hd->BURST_DAT,(unsigned int)hd->SPI_FL_DAT,(unsigned int)hd->MISC_CTL,(unsigned int)hd->reserved_0x12,(unsigned int)hd->FIRMW_START,
        (unsigned int)hd->FIRMW_SIZE,(unsigned int)hd->HEADER_CKSM,(unsigned int)hd->reserved_0x42,(unsigned int)hd->FIRMW_CKSM);
    printf("Calculated hearder crc=%04x\n",csum);
    fseek(fd,hd->FIRMW_START-0x020000,SEEK_SET);
    buf2=malloc(hd->FIRMW_SIZE*2);
    if(buf2==NULL)
    {
        printf("failed to allocate memory %u\n",hd->FIRMW_SIZE);
        exit(1);
    }
    sz=fread(buf2,hd->FIRMW_SIZE*2,1,fd);
    if(sz!=1)
    {
        printf("failed to read a file %s\n",argv[1]);
        free(buf2);
        exit(1);
    }
    for(k=0;k<hd->FIRMW_SIZE*2;k++)
        csum2+=buf2[k];
    printf("Calculated firmware crc=%08x\n",csum2);
    if( (csum == hd->HEADER_CKSM) && (csum2 == hd->FIRMW_CKSM))
        printf("Checksums OK\n");
    else{
        hd->HEADER_CKSM=csum;
        hd->FIRMW_CKSM=csum2;
        fseek(fd,0,SEEK_SET);
        if(fwrite(hd,sizeof(struct header_data),1,fd)==1)
            printf("Checksums Updated\n");
        else
            printf("Checksum update failed.\n");
    }
    free(buf2);

    fclose(fd);
}