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base/Int8

Provides utility functions on 8-bit signed integers.

Function form for higher-order use

Several arithmetic and comparison functions (e.g. add, sub, bitor, bitand, pow) are defined in this module to enable their use as first-class function values, which is not possible with operators like +, -, ==, etc., in Motoko. This allows you to pass these operations to higher-order functions such as map, foldLeft, or sort.

Most operations are available as built-in operators (e.g. 1 + 1).

Import from the base library to use this module.

import Int8 "mo:base/Int8";

Type Int8​

type Int8 = Prim.Types.Int8

8-bit signed integers.

Value minimumValue​

let minimumValue : Int8

Minimum 8-bit integer value, -2 ** 7.

Example:

Int8.minimumValue // => -128

Value maximumValue​

let maximumValue : Int8

Maximum 8-bit integer value, +2 ** 7 - 1.

Example:

Int8.maximumValue // => +127

Function toInt​

func toInt(_ : Int8) : Int

Converts an 8-bit signed integer to a signed integer with infinite precision.

Example:

Int8.toInt(123) // => 123 : Int

Function fromInt​

func fromInt(_ : Int) : Int8

Converts a signed integer with infinite precision to an 8-bit signed integer.

Traps on overflow/underflow.

Example:

Int8.fromInt(123) // => +123 : Int8

Function fromIntWrap​

func fromIntWrap(_ : Int) : Int8

Converts a signed integer with infinite precision to an 8-bit signed integer.

Wraps on overflow/underflow.

Example:

Int8.fromIntWrap(-123) // => -123 : Int

Function fromInt16​

func fromInt16(_ : Int16) : Int8

Converts a 16-bit signed integer to an 8-bit signed integer.

Traps on overflow/underflow.

Example:

Int8.fromInt16(123) // => +123 : Int8

Function toInt16​

func toInt16(_ : Int8) : Int16

Converts an 8-bit signed integer to a 16-bit signed integer.

Example:

Int8.toInt16(123) // => +123 : Int16

Function fromNat8​

func fromNat8(_ : Nat8) : Int8

Converts an unsigned 8-bit integer to a signed 8-bit integer.

Wraps on overflow/underflow.

Example:

Int8.fromNat8(123) // => +123 : Int8

Function toNat8​

func toNat8(_ : Int8) : Nat8

Converts a signed 8-bit integer to an unsigned 8-bit integer.

Wraps on overflow/underflow.

Example:

Int8.toNat8(-1) // => 255 : Nat8 // underflow

Function toText​

func toText(x : Int8) : Text

Converts an integer number to its textual representation.

Example:

Int8.toText(-123) // => "-123"

Function abs​

func abs(x : Int8) : Int8

Returns the absolute value of x.

Traps when x == -2 ** 7 (the minimum Int8 value).

Example:

Int8.abs(-123) // => +123

Function min​

func min(x : Int8, y : Int8) : Int8

Returns the minimum of x and y.

Example:

Int8.min(+2, -3) // => -3

Function max​

func max(x : Int8, y : Int8) : Int8

Returns the maximum of x and y.

Example:

Int8.max(+2, -3) // => +2

Function equal​

func equal(x : Int8, y : Int8) : Bool

Equality function for Int8 types. This is equivalent to x == y.

Example:

Int8.equal(-1, -1); // => true

Example:

import Buffer "mo:base/Buffer";

let buffer1 = Buffer.Buffer<Int8>(1);
buffer1.add(-3);
let buffer2 = Buffer.Buffer<Int8>(1);
buffer2.add(-3);
Buffer.equal(buffer1, buffer2, Int8.equal) // => true

Function notEqual​

func notEqual(x : Int8, y : Int8) : Bool

Inequality function for Int8 types. This is equivalent to x != y.

Example:

Int8.notEqual(-1, -2); // => true

Function less​

func less(x : Int8, y : Int8) : Bool

"Less than" function for Int8 types. This is equivalent to x < y.

Example:

Int8.less(-2, 1); // => true

Function lessOrEqual​

func lessOrEqual(x : Int8, y : Int8) : Bool

"Less than or equal" function for Int8 types. This is equivalent to x <= y.

Example:

Int8.lessOrEqual(-2, -2); // => true

Function greater​

func greater(x : Int8, y : Int8) : Bool

"Greater than" function for Int8 types. This is equivalent to x > y.

Example:

Int8.greater(-2, -3); // => true

Function greaterOrEqual​

func greaterOrEqual(x : Int8, y : Int8) : Bool

"Greater than or equal" function for Int8 types. This is equivalent to x >= y.

Example:

Int8.greaterOrEqual(-2, -2); // => true

Function compare​

func compare(x : Int8, y : Int8) : {#less; #equal; #greater}

General-purpose comparison function for Int8. Returns the Order ( either #less, #equal, or #greater) of comparing x with y.

Example:

Int8.compare(-3, 2) // => #less

This function can be used as value for a high order function, such as a sort function.

Example:

import Array "mo:base/Array";
Array.sort([1, -2, -3] : [Int8], Int8.compare) // => [-3, -2, 1]

Function neg​

func neg(x : Int8) : Int8

Returns the negation of x, -x.

Traps on overflow, i.e. for neg(-2 ** 7).

Example:

Int8.neg(123) // => -123

Function add​

func add(x : Int8, y : Int8) : Int8

Returns the sum of x and y, x + y.

Traps on overflow/underflow.

Example:

Int8.add(100, 23) // => +123

Example:

import Array "mo:base/Array";
Array.foldLeft<Int8, Int8>([1, -2, -3], 0, Int8.add) // => -4

Function sub​

func sub(x : Int8, y : Int8) : Int8

Returns the difference of x and y, x - y.

Traps on overflow/underflow.

Example:

Int8.sub(123, 23) // => +100

Example:

import Array "mo:base/Array";
Array.foldLeft<Int8, Int8>([1, -2, -3], 0, Int8.sub) // => 4

Function mul​

func mul(x : Int8, y : Int8) : Int8

Returns the product of x and y, x * y.

Traps on overflow/underflow.

Example:

Int8.mul(12, 10) // => +120

Example:

import Array "mo:base/Array";
Array.foldLeft<Int8, Int8>([1, -2, -3], 1, Int8.mul) // => 6

Function div​

func div(x : Int8, y : Int8) : Int8

Returns the signed integer division of x by y, x / y. Rounds the quotient towards zero, which is the same as truncating the decimal places of the quotient.

Traps when y is zero.

Example:

Int8.div(123, 10) // => +12

Function rem​

func rem(x : Int8, y : Int8) : Int8

Returns the remainder of the signed integer division of x by y, x % y, which is defined as x - x / y * y.

Traps when y is zero.

Example:

Int8.rem(123, 10) // => +3

Function pow​

func pow(x : Int8, y : Int8) : Int8

Returns x to the power of y, x ** y.

Traps on overflow/underflow and when y < 0 or y >= 8.

Example:

Int8.pow(2, 6) // => +64

Function bitnot​

func bitnot(x : Int8) : Int8

Returns the bitwise negation of x, ^x.

Example:

Int8.bitnot(-16 /* 0xf0 */) // => +15 // 0x0f

Function bitand​

func bitand(x : Int8, y : Int8) : Int8

Returns the bitwise "and" of x and y, x & y.

Example:

Int8.bitand(0x1f, 0x70) // => +16 // 0x10

Function bitor​

func bitor(x : Int8, y : Int8) : Int8

Returns the bitwise "or" of x and y, x | y.

Example:

Int8.bitor(0x0f, 0x70) // => +127 // 0x7f

Function bitxor​

func bitxor(x : Int8, y : Int8) : Int8

Returns the bitwise "exclusive or" of x and y, x ^ y.

Example:

Int8.bitxor(0x70, 0x7f) // => +15 // 0x0f

Function bitshiftLeft​

func bitshiftLeft(x : Int8, y : Int8) : Int8

Returns the bitwise left shift of x by y, x << y. The right bits of the shift filled with zeros. Left-overflowing bits, including the sign bit, are discarded.

For y >= 8, the semantics is the same as for bitshiftLeft(x, y % 8). For y < 0, the semantics is the same as for bitshiftLeft(x, y + y % 8).

Example:

Int8.bitshiftLeft(1, 4) // => +16 // 0x10 equivalent to `2 ** 4`.

Function bitshiftRight​

func bitshiftRight(x : Int8, y : Int8) : Int8

Returns the signed bitwise right shift of x by y, x >> y. The sign bit is retained and the left side is filled with the sign bit. Right-underflowing bits are discarded, i.e. not rotated to the left side.

For y >= 8, the semantics is the same as for bitshiftRight(x, y % 8). For y < 0, the semantics is the same as for bitshiftRight (x, y + y % 8).

Example:

Int8.bitshiftRight(64, 4) // => +4 // equivalent to `64 / (2 ** 4)`

Function bitrotLeft​

func bitrotLeft(x : Int8, y : Int8) : Int8

Returns the bitwise left rotatation of x by y, x <<> y. Each left-overflowing bit is inserted again on the right side. The sign bit is rotated like other bits, i.e. the rotation interprets the number as unsigned.

Changes the direction of rotation for negative y. For y >= 8, the semantics is the same as for bitrotLeft(x, y % 8).

Example:

Int8.bitrotLeft(0x11 /* 0b0001_0001 */, 2) // => +68 // 0b0100_0100 == 0x44.

Function bitrotRight​

func bitrotRight(x : Int8, y : Int8) : Int8

Returns the bitwise right rotation of x by y, x <>> y. Each right-underflowing bit is inserted again on the right side. The sign bit is rotated like other bits, i.e. the rotation interprets the number as unsigned.

Changes the direction of rotation for negative y. For y >= 8, the semantics is the same as for bitrotRight(x, y % 8).

Example:

Int8.bitrotRight(0x11 /* 0b0001_0001 */, 1) // => -120 // 0b1000_1000 == 0x88.

Function bittest​

func bittest(x : Int8, p : Nat) : Bool

Returns the value of bit p in x, x & 2**p == 2**p. If p >= 8, the semantics is the same as for bittest(x, p % 8). This is equivalent to checking if the p-th bit is set in x, using 0 indexing.

Example:

Int8.bittest(64, 6) // => true

Function bitset​

func bitset(x : Int8, p : Nat) : Int8

Returns the value of setting bit p in x to 1. If p >= 8, the semantics is the same as for bitset(x, p % 8).

Example:

Int8.bitset(0, 6) // => +64

Function bitclear​

func bitclear(x : Int8, p : Nat) : Int8

Returns the value of clearing bit p in x to 0. If p >= 8, the semantics is the same as for bitclear(x, p % 8).

Example:

Int8.bitclear(-1, 6) // => -65

Function bitflip​

func bitflip(x : Int8, p : Nat) : Int8

Returns the value of flipping bit p in x. If p >= 8, the semantics is the same as for bitclear(x, p % 8).

Example:

Int8.bitflip(127, 6) // => +63

Function bitcountNonZero​

func bitcountNonZero(x : Int8) : Int8

Returns the count of non-zero bits in x.

Example:

Int8.bitcountNonZero(0x0f) // => +4

Function bitcountLeadingZero​

func bitcountLeadingZero(x : Int8) : Int8

Returns the count of leading zero bits in x.

Example:

Int8.bitcountLeadingZero(0x08) // => +4

Function bitcountTrailingZero​

func bitcountTrailingZero(x : Int8) : Int8

Returns the count of trailing zero bits in x.

Example:

Int8.bitcountTrailingZero(0x10) // => +4

Function addWrap​

func addWrap(x : Int8, y : Int8) : Int8

Returns the sum of x and y, x +% y.

Wraps on overflow/underflow.

Example:

Int8.addWrap(2 ** 6, 2 ** 6) // => -128 // overflow

Function subWrap​

func subWrap(x : Int8, y : Int8) : Int8

Returns the difference of x and y, x -% y.

Wraps on overflow/underflow.

Example:

Int8.subWrap(-2 ** 7, 1) // => +127 // underflow

Function mulWrap​

func mulWrap(x : Int8, y : Int8) : Int8

Returns the product of x and y, x *% y. Wraps on overflow.

Wraps on overflow/underflow.

Example:

Int8.mulWrap(2 ** 4, 2 ** 4) // => 0 // overflow

Function powWrap​

func powWrap(x : Int8, y : Int8) : Int8

Returns x to the power of y, x **% y.

Wraps on overflow/underflow. Traps if y < 0 or y >= 8.

Example:

Int8.powWrap(2, 7) // => -128 // overflow