Getting Started

Orbs Contracts

Gamma in Depth

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API Reference

This page is used to describe all the additional APIs which exists as part of the Contract SDK.

Env

To use the

`Env`

package, you need to import it:1

import (

2

"github.com/orbs-network/orbs-contract-sdk/go/sdk/v1/env"

3

)

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It provides the following functions:

GetBlockHeight

Used to get the block height which will be the one this transaction be a part of

1

GetBlockHeight() uint64

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It returns the block height in decimal values:

GetBlockTimestamp

Used to get the block timestamp (creation time) which will be the one this transaction be a part of:

1

GetBlockTimestamp() uint64

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It returns the block timestamp representing the Unix epoch in nanoseconds.

GetVirtualChainId

Used to get the virtual chain id this contract is executing on.

1

GetVirtualChainId() uint32

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It returns the virtual chain id in decimal values.

Safemath

To use the

`Safemath`

package, you need to import it:1

import (

2

"github.com/orbs-network/orbs-contract-sdk/go/sdk/v1/safemath/safeuint256"

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"github.com/orbs-network/orbs-contract-sdk/go/sdk/v1/safemath/safeuint64"

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"github.com/orbs-network/orbs-contract-sdk/go/sdk/v1/safemath/safeuint32"

5

)

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It gives the ability to work with 32, 64, and 256 bit unsigned integers in a 'safe' way meaning there is an overflow/underflow and illegal operation protection around the arithmetic operation done.

The API is uniform between the different variants and consist of the following functions:

Add

Adds two numbers and returns the result. The numbers are validated so that they do not overflow after the addition.

1

Add(x *big.Int, y *big.Int) *big.Int

2

Add(x uint32, y uint32) uint32

3

Add(x uint64, y uint64) uint64

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Sub

Subtract

`y`

from `x`

. The result is validated, so if it becomes negative, an error is returned.1

Sub(x *big.Int, y *big.Int) *big.Int

2

Sub(x uint32, y uint32) uint32

3

Sub(x uint64, y uint64) uint64

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Mul

Multiplies the values and returns the new number. The result is validated so that it does not overflow.

1

Mul(x *big.Int, y *big.Int) *big.Int

2

Mul(x uint32, y uint32) uint32

3

Mul(x uint64, y uint64) uint64

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Div

Performs an integer division of

`x`

by `y`

. The remainder is discarded as it should in integer arithmetic, and the input (`y`

) is validated not to be zero.1

Div(x *big.Int, y *big.Int) *big.Int

2

Div(x uint32, y uint32) uint32

3

Div(x uint64, y uint64) uint64

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Mod

Performs the modulo operation of

`x`

by `y`

. The input is validated to be valid (meaning `y`

is not zero). The resulting number is the reminder.1

Mod(x *big.Int, y *big.Int) *big.Int

2

Mod(x uint32, y uint32) uint32

3

Mod(x uint64, y uint64) uint64

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Validate

Only relevant for

`safeuint256`

The function validates that the number is not negative, and did not overflow. If the validation fails, the code panics with the appropriate message.

1

Validate(n *big.Int)

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Note that

`validate`

is called automatically on each operation, meaning after using `Add`

or `Sub`

or any operation of the safemath library, so there is no need to call it manually.Orbs Contracts - Previous

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