Feature request

Hi,
I'm cracking network unlock code of my phone.
I read hashcat's mannual and did not find where to customize the process that matches my requirements.
Do you have any ideas? Or is there a SDK?

For reference, it's verification is like this:
// those are predefined
char salt[20];
char expected[32];
// result hash
char hash[32];
// user input, numberic only
char code[?];
char buffer[64];

// 1st round
len = strlen(code);
memcpy(buffer, code, len);
memcpy(buffer + len, salt, 20);
SHA256_Transform(buffer, len + 20, hash); // output result into hash
// left rounds
for (i = 0; i < 9; i++) {
SHA256_Transform(hash, 32, hash);
}
//
if (!memcmp(expected, hash, 32))
passed();