What is this "Jetton-ICO-Minter.fc" FunC file talks about? (Each line overview for questions)

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First, I am learning the FunC in general. And watchs in example is the best way to learn a langaugae.

in Line 41, why we set a slice-cell to read for an unsigned integer 4?

() recv_internal(int msg_value, cell in_msg_full, slice in_msg_body) impure {
    slice cs = in_msg_full.begin_parse();
    int flags = cs~load_uint(4);

    if (flags & 1) { ;; ignore all bounced messages
        return ();
--------- more ------

There is no proper explain for load_data even in https://ton.org/docs/develop

https://github.com/ton-blockchain/token-contract/blob/f2253cb0f0e1ae0974d7dc0cef3a62cb6e19f806/ft/jetton-minter-ICO.fc#L48

What is throw_unless means in Line 54

throw_unless(76, buy_amount > 0);

What is 76 here means?

In line 28, there has a word calculate_jetton_wallet_address, but can't find any place in second time. What is this function coming from?
In Line 18 what is the 0x18 means? and why it is store with 6 bits?

  				
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	one year ago

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					Howard
				
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First 4 bits for the message like below

0 for internal, 1 for external message
0 for enable instant hypercube routing, 1 for disable (it is not implemented yet, so always 1 now)
1 for bouncible message, 0 for not
1 for result of bouncing itself, 0 for not

load_data function is used for load contract's storage. And contract developer have to implement this for each contract. Please refer https://github.com/ton-blockchain/token-contract/blob/f2253cb0f0e1ae0974d7dc0cef3a62cb6e19f806/ft/jetton-minter-ICO.fc#L6-L14
76 is error code when throw_unless function throw exception. And this function throws when second parameter's result is false. So it throws when buy_amount == 0
It is in https://github.com/ton-blockchain/token-contract/blob/f2253cb0f0e1ae0974d7dc0cef3a62cb6e19f806/ft/jetton-utils.fc
Please refer https://ton.org/docs/develop/smart-contracts/messages and first question's answer. After that 4 bits, 2bits are set 0b00, it means empty address and it will be handled same as sender_address.

  				
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	one year ago

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					junmo
				
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one year ago