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updated cairo.html.markdown
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Darlington02
parent
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@ -180,7 +180,7 @@ func increase_balance{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*,
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let (res) = balance.read();
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balance.write(res + amount);
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return ();
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}
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}
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// @dev returns the balance variable
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// @view is a decorator that specifies the func below it is a view function.
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@ -189,7 +189,7 @@ func get_balance{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*,
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range_check_ptr}() -> (res: felt) {
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let (res) = balance.read();
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return (res,);
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}
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}
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```
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Before proceeding to the main lessons, try to build, deploy and interact with
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@ -204,10 +204,10 @@ just a single data type `..felts`. Felts stands for Field elements, and are a
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create a `Uint256` in Cairo by utlizing a struct of two 128 bits felts.
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```cairo
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struct Uint256{
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struct Uint256 {
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low: felt, // The low 128 bits of the value.
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high: felt, // The high 128 bits of the value.
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}
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}
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```
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To avoid running into issues with divisions, it's safer to work with the
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@ -239,19 +239,19 @@ from starkware.cairo.common.bool import TRUE
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+ Storage variables: Cairo's storage is a map with `2^251` slots, where each
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slot is a felt which is initialized to `0`. You create one using the
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`@storage_var` decorator
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`@storage_var` decorator.
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```cairo
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@storage_var
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func names() -> (name: felt){}
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func names() -> (name: felt) {}
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```
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+ Storage mappings: Unlike soldity where mappings have a separate keyword, in
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+ Storage mappings: Unlike Solidity where mappings have a separate keyword, in
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Cairo you create mappings using storage variables.
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```cairo
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@storage_var
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func names(address: felt) -> (name: felt){}
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func names(address: felt) -> (name: felt) {}
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```
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+ Structs: are a means to create custom data types in Cairo. A `struct` has a
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@ -269,7 +269,7 @@ from starkware.cairo.common.bool import TRUE
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+ Constants: Constants are fixed and as such can't be altered after being set.
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They evaluate to an integer (field element) at compile time. To create a
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constant in Cairo, you use the `const` keyword. Its proper practice to
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constant in Cairo, you use the `const` keyword. It's proper practice to
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capitalize constant names.
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```cairo
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@ -423,11 +423,11 @@ Here are the most common decorators you'll encounter in Cairo:
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```cairo
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func store_name{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*,
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range_check_ptr}(_name: felt){
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let (caller) = get_caller_address();
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names.write(caller, _name);
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stored_name.emit(caller, _name);
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return ();
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range_check_ptr}(_name: felt){
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let (caller) = get_caller_address();
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names.write(caller, _name);
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stored_name.emit(caller, _name);
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return ();
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}
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```
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@ -479,12 +479,12 @@ contract passing in the contract address as the first parameter like this:
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IENS.store_name(contract_address, _name);
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```
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Note that Interfaces excludes the function body/logic and the implicit
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Note that Interfaces exclude the function body/logic and the implicit
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arguments.
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### 9. Recursions
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Due to the unavailability of loops, Recursions are the go-to for similar
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Due to the unavailability of loops, Recursion is the go-to for similar
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operations. In simple terms, a recursive function is one which calls itself
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repeatedly.
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@ -494,25 +494,25 @@ fibonacci number:
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```cairo
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@external
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func fibonacci{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*,
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range_check_ptr}(n : felt) -> (result : felt){
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alloc_locals;
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if (n == 0){
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return (0);
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}
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if (n == 1){
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return (1);
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}
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let (local x) = fibonacci(n - 1);
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let (local y) = fibonacci(n - 2);
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return (result=(x + y));
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range_check_ptr}(n : felt) -> (result : felt){
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alloc_locals;
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if (n == 0){
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return (0);
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}
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if (n == 1){
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return (1);
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}
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let (local x) = fibonacci(n - 1);
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let (local y) = fibonacci(n - 2);
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return (result=(x + y));
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}
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```
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The nth fibonacci term is the sum of the `nth - 1` and the `nth - 2` numbers,
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that's why we get these two as `(x,y)` using recursion.
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NB: when implementing recursive functions, always remember to implement a base
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case (`n==0`, `n==1` in our case), to prevent stack overflow.
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case (`n==0`, `n==1` in our case), to prevent stack overflows.
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### 10. Registers
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@ -529,8 +529,8 @@ registers:
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### 11. Revoked References
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Revoked references occurs when there is a call instruction to another function,
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between the definition of a reference variable that depends on `ap`(temp
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Revoked references occur when there is a call instruction to another function,
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between the definition of a reference variable that depends on `ap` (temp
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variables) and its usage. This occurs as the compiler may not be able to compute
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the change of `ap` (as one may jump to the label from another place in the
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program, or call a function that might change ap in an unknown way).
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@ -540,18 +540,18 @@ Here is an example to demonstrate what I mean:
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```cairo
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@external
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func get_balance{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*,
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range_check_ptr}() -> (res: felt) {
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return (res=100);
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}
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range_check_ptr}() -> (res: felt) {
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return (res=100);
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}
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@external
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func double_balance{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*,
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range_check_ptr}() -> (res: felt) {
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let multiplier = 2;
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let (balance) = get_balance();
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let new_balance = balance * multiplier;
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return (res=new_balance);
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}
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range_check_ptr}() -> (res: felt) {
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let multiplier = 2;
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let (balance) = get_balance();
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let new_balance = balance * multiplier;
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return (res=new_balance);
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}
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```
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If you run that code, you'll run into the revoked reference error as we are
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@ -559,20 +559,20 @@ trying to access the `multiplier` variable after calling the `get_balance`
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function.
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In simple cases you can resolve revoked references by adding the keyword
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`alloc_locals` within function scopes. In most complex cases you might need to
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`alloc_locals` within function scopes. In more complex cases you might need to
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create a local variable to resolve it.
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```cairo
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// resolving the `double_balance` function:
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@external
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func double_balance{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*,
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range_check_ptr}() -> (res: felt) {
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alloc_locals;
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let multiplier = 2;
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let (balance) = get_balance();
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let new_balance = balance * multiplier;
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return (res=new_balance);
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}
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range_check_ptr}() -> (res: felt) {
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alloc_locals;
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let multiplier = 2;
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let (balance) = get_balance();
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let new_balance = balance * multiplier;
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return (res=new_balance);
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}
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```
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### 12. Understanding Cairo's Punctuations
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@ -627,7 +627,7 @@ const ACCOUNT_BALANCE_BOUND = 1073741; // (2 ** 30 / 1000)
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//
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// @dev A map from account and token type to corresponding balance
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@storage_var
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func account_balance(account_id: felt, token_type: felt) -> (balance: felt){}
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func account_balance(account_id: felt, token_type: felt) -> (balance: felt) {}
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// @dev a map from token type to corresponding pool balance
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@storage_var
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@ -641,21 +641,21 @@ func pool_balance(token_type: felt) -> (balance: felt) {}
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// @param token_type Token to be queried
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@view
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func get_account_token_balance{syscall_ptr: felt*, pedersen_ptr:
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HashBuiltin*, range_check_ptr}(
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account_id: felt, token_type: felt
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) -> (balance: felt) {
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return account_balance.read(account_id, token_type);
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}
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HashBuiltin*, range_check_ptr}(
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account_id: felt, token_type: felt
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) -> (balance: felt) {
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return account_balance.read(account_id, token_type);
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}
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// @dev return the pool's balance
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// @param token_type Token type to get pool balance
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@view
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func get_pool_token_balance{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*,
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range_check_ptr}(
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token_type: felt
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) -> (balance: felt) {
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return pool_balance.read(token_type);
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}
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range_check_ptr}(
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token_type: felt
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) -> (balance: felt) {
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return pool_balance.read(token_type);
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}
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// EXTERNALS
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@ -665,55 +665,55 @@ func get_pool_token_balance{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*,
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// @param balance Amount to be set as balance
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@external
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func set_pool_token_balance{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*,
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range_check_ptr}(
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token_type: felt, balance: felt
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) {
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with_attr error_message("exceeds maximum allowed tokens!"){
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assert_nn_le(balance, BALANCE_UPPER_BOUND - 1);
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}
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range_check_ptr}(
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token_type: felt, balance: felt
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) {
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with_attr error_message("exceeds maximum allowed tokens!"){
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assert_nn_le(balance, BALANCE_UPPER_BOUND - 1);
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}
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pool_balance.write(token_type, balance);
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return ();
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}
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}
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// @dev add demo token to the given account
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// @param token_a_amount amount of token a to be added
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// @param token_b_amount amount of token b to be added
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@external
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func add_demo_token{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*,
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range_check_ptr}(
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range_check_ptr}(
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token_a_amount: felt, token_b_amount: felt
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) {
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alloc_locals;
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let (account_id) = get_caller_address();
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alloc_locals;
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let (account_id) = get_caller_address();
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modify_account_balance(account_id=account_id, token_type=TOKEN_TYPE_A,
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amount=token_a_amount);
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modify_account_balance(account_id=account_id, token_type=TOKEN_TYPE_B,
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amount=token_b_amount);
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modify_account_balance(account_id=account_id, token_type=TOKEN_TYPE_A,
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amount=token_a_amount);
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modify_account_balance(account_id=account_id, token_type=TOKEN_TYPE_B,
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amount=token_b_amount);
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return ();
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}
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return ();
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}
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// @dev intialize AMM
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// @param token_a amount of token a to be set in pool
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// @param token_b amount of token b to be set in pool
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@external
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func init_pool{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*,
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range_check_ptr}(
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token_a: felt, token_b: felt
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) {
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with_attr error_message("exceeds maximum allowed tokens!"){
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assert_nn_le(token_a, POOL_UPPER_BOUND - 1);
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assert_nn_le(token_b, POOL_UPPER_BOUND - 1);
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}
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set_pool_token_balance(token_type=TOKEN_TYPE_A, balance=token_a);
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set_pool_token_balance(token_type=TOKEN_TYPE_B, balance=token_b);
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return ();
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range_check_ptr}(
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token_a: felt, token_b: felt
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) {
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with_attr error_message("exceeds maximum allowed tokens!"){
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assert_nn_le(token_a, POOL_UPPER_BOUND - 1);
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assert_nn_le(token_b, POOL_UPPER_BOUND - 1);
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}
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set_pool_token_balance(token_type=TOKEN_TYPE_A, balance=token_a);
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set_pool_token_balance(token_type=TOKEN_TYPE_B, balance=token_b);
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return ();
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}
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// @dev swaps token between the given account and the pool
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// @param token_from token to be swapped
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@ -723,32 +723,32 @@ func init_pool{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*,
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func swap{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*, range_check_ptr}(
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token_from: felt, amount_from: felt
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) -> (amount_to: felt) {
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alloc_locals;
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let (account_id) = get_caller_address();
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alloc_locals;
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let (account_id) = get_caller_address();
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// verify token_from is TOKEN_TYPE_A or TOKEN_TYPE_B
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with_attr error_message("token not allowed in pool!"){
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assert (token_from - TOKEN_TYPE_A) * (token_from - TOKEN_TYPE_B) = 0;
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}
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// verify token_from is TOKEN_TYPE_A or TOKEN_TYPE_B
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with_attr error_message("token not allowed in pool!"){
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assert (token_from - TOKEN_TYPE_A) * (token_from - TOKEN_TYPE_B) = 0;
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}
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// check requested amount_from is valid
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with_attr error_message("exceeds maximum allowed tokens!"){
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assert_nn_le(amount_from, BALANCE_UPPER_BOUND - 1);
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}
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// check requested amount_from is valid
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with_attr error_message("exceeds maximum allowed tokens!"){
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assert_nn_le(amount_from, BALANCE_UPPER_BOUND - 1);
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}
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// check user has enough funds
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let (account_from_balance) =
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get_account_token_balance(account_id=account_id, token_type=token_from);
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with_attr error_message("insufficient balance!"){
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assert_le(amount_from, account_from_balance);
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}
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// check user has enough funds
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let (account_from_balance) =
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get_account_token_balance(account_id=account_id, token_type=token_from);
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with_attr error_message("insufficient balance!"){
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assert_le(amount_from, account_from_balance);
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}
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let (token_to) = get_opposite_token(token_type=token_from);
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let (amount_to) = do_swap(account_id=account_id, token_from=token_from,
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token_to=token_to, amount_from=amount_from);
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let (token_to) = get_opposite_token(token_type=token_from);
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let (amount_to) = do_swap(account_id=account_id, token_from=token_from,
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token_to=token_to, amount_from=amount_from);
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return (amount_to=amount_to);
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}
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return (amount_to=amount_to);
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}
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// INTERNALS
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@ -761,17 +761,17 @@ func modify_account_balance{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*,
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range_check_ptr}(
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account_id: felt, token_type: felt, amount: felt
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) {
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let (current_balance) = account_balance.read(account_id, token_type);
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tempvar new_balance = current_balance + amount;
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let (current_balance) = account_balance.read(account_id, token_type);
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tempvar new_balance = current_balance + amount;
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with_attr error_message("exceeds maximum allowed tokens!"){
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assert_nn_le(new_balance, BALANCE_UPPER_BOUND - 1);
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}
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with_attr error_message("exceeds maximum allowed tokens!"){
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assert_nn_le(new_balance, BALANCE_UPPER_BOUND - 1);
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}
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account_balance.write(account_id=account_id, token_type=token_type,
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value=new_balance);
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return ();
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}
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account_balance.write(account_id=account_id, token_type=token_type,
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value=new_balance);
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return ();
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}
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// @dev internal function that swaps tokens between the given account and
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// the pool
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@ -783,31 +783,31 @@ func do_swap{syscall_ptr: felt*, pedersen_ptr: HashBuiltin*,
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range_check_ptr}(
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account_id: felt, token_from: felt, token_to: felt, amount_from: felt
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) -> (amount_to: felt) {
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alloc_locals;
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alloc_locals;
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// get pool balance
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let (local amm_from_balance) = get_pool_token_balance(token_type =
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token_from);
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let (local amm_to_balance) = get_pool_token_balance(token_type=token_to);
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// get pool balance
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let (local amm_from_balance) = get_pool_token_balance(token_type =
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token_from);
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let (local amm_to_balance) = get_pool_token_balance(token_type=token_to);
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// calculate swap amount
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let (local amount_to, _) = unsigned_div_rem((amm_to_balance *
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amount_from), (amm_from_balance + amount_from));
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// calculate swap amount
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let (local amount_to, _) = unsigned_div_rem((amm_to_balance *
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amount_from), (amm_from_balance + amount_from));
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// update token_from balances
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modify_account_balance(account_id=account_id, token_type=token_from,
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amount=-amount_from);
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set_pool_token_balance(token_type=token_from, balance=(amm_from_balance
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+ amount_from));
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// update token_from balances
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modify_account_balance(account_id=account_id, token_type=token_from,
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amount=-amount_from);
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set_pool_token_balance(token_type=token_from, balance=(amm_from_balance
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+ amount_from));
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// update token_to balances
|
||||
modify_account_balance(account_id=account_id, token_type=token_to,
|
||||
amount=amount_to);
|
||||
set_pool_token_balance(token_type=token_to, balance=(amm_to_balance -
|
||||
amount_to));
|
||||
// update token_to balances
|
||||
modify_account_balance(account_id=account_id, token_type=token_to,
|
||||
amount=amount_to);
|
||||
set_pool_token_balance(token_type=token_to, balance=(amm_to_balance -
|
||||
amount_to));
|
||||
|
||||
return (amount_to=amount_to);
|
||||
}
|
||||
return (amount_to=amount_to);
|
||||
}
|
||||
|
||||
|
||||
// @dev internal function to get the opposite token type
|
||||
|
||||
Loading…
Reference in New Issue
Block a user