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https://codeberg.org/ziglings/exercises.git
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fb46871dab
...
97c2ea2f49
11 changed files with 53 additions and 191 deletions
31
.devcontainer/devcontainer.json
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31
.devcontainer/devcontainer.json
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@ -0,0 +1,31 @@
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// For format details, see https://aka.ms/devcontainer.json. For config options, see the
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// README at: https://github.com/devcontainers/templates/tree/main/src/debian
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{
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"name": "Ziglings",
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// Or use a Dockerfile or Docker Compose file. More info: https://containers.dev/guide/dockerfile
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"image": "mcr.microsoft.com/devcontainers/base:bullseye",
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"features": {
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"ghcr.io/devcontainers-contrib/features/zig:1": {
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"version": "master"
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}
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},
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"customizations": {
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"vscode": {
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"extensions": [
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"ziglang.vscode-zig"
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]
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}
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}
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// Features to add to the dev container. More info: https://containers.dev/features.
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// "features": {},
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// Use 'forwardPorts' to make a list of ports inside the container available locally.
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// "forwardPorts": [],
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// Configure tool-specific properties.
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// "customizations": {},
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// Uncomment to connect as root instead. More info: https://aka.ms/dev-containers-non-root.
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// "remoteUser": "root"
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}
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@ -1201,13 +1201,6 @@ const exercises = [_]Exercise{
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.main_file = "108_labeled_switch.zig",
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.output = "The pull request has been merged.",
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},
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.{
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.main_file = "109_vectors.zig",
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.output =
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\\Max difference (old fn): 0.014
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\\Max difference (new fn): 0.014
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,
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},
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.{
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.main_file = "999_the_end.zig",
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.output =
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@ -190,7 +190,7 @@ const TripItem = union(enum) {
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fn printMe(self: TripItem) void {
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switch (self) {
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// Oops! The hermit forgot how to capture the union values
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// in a switch statement. Please capture each value as
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// in a switch statement. Please capture both values as
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// 'p' so the print statements work!
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.place => print("{s}", .{p.name}),
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.path => print("--{}->", .{p.dist}),
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@ -110,15 +110,15 @@ pub fn main() void {
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// name will not be printed if the field is of type 'void'
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// (which is a zero-bit type that takes up no space at all!):
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if (fields[0].??? != void) {
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print(" {s}", .{fields[0].name});
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print(" {s}", .{@typeInfo(Narcissus).@"struct".fields[0].name});
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}
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if (fields[1].??? != void) {
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print(" {s}", .{fields[1].name});
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print(" {s}", .{@typeInfo(Narcissus).@"struct".fields[1].name});
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}
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if (fields[2].??? != void) {
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print(" {s}", .{fields[2].name});
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print(" {s}", .{@typeInfo(Narcissus).@"struct".fields[2].name});
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}
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// Yuck, look at all that repeated code above! I don't know
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@ -136,16 +136,14 @@ pub fn main() void {
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// But a change after Zig 0.10.0 added the source file name to the
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// type. "Narcissus" became "065_builtins2.Narcissus".
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//
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// To fix this, we've added this function to strip the filename from
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// the front of the type name. (It returns a slice of the type name
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// starting at the index + 1 of character ".")
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// To fix this, I've added this function to strip the filename from
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// the front of the type name in the dumbest way possible. (It returns
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// a slice of the type name starting at character 14 (assuming
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// single-byte characters).
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//
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// We'll be seeing @typeName again in Exercise 070. For now, you can
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// see that it takes a Type and returns a u8 "string".
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fn maximumNarcissism(myType: anytype) []const u8 {
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const indexOf = @import("std").mem.indexOf;
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// Turn "065_builtins2.Narcissus" into "Narcissus"
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const name = @typeName(myType);
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return name[indexOf(u8, name, ".").? + 1 ..];
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// Turn '065_builtins2.Narcissus' into 'Narcissus'
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return @typeName(myType)[14..];
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}
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@ -16,7 +16,7 @@
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// Therefore, the comments for the format() function are the only
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// way to definitively learn how to format strings in Zig:
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//
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// https://github.com/ziglang/zig/blob/master/lib/std/fmt.zig#L33
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// https://github.com/ziglang/zig/blob/master/lib/std/fmt.zig#L29
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//
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// Zig already has a very nice selection of formatting options.
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// These can be used in different ways, but generally to convert
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@ -39,7 +39,7 @@
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// in practice. Because either you don't need the precision, or you use a
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// calculator in which the number is stored as a very precise constant.
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// But at some point this constant was calculated and we are doing the same
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// now. The question at this point is, how many partial values do we have
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// now.The question at this point is, how many partial values do we have
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// to calculate for which accuracy?
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//
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// The answer is chewing, to get 8 digits after the decimal point we need
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@ -1,147 +0,0 @@
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// So far in Ziglings, we've seen how for loops can be used to
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// repeat calculations across an array in several ways.
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//
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// For loops are generally great for this kind of task, but
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// sometimes they don't fully utilize the capabilities of the
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// CPU.
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//
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// Most modern CPUs can execute instructions in which SEVERAL
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// calculations are performed WITHIN registers at the SAME TIME.
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// These are known as "single instruction, multiple data" (SIMD)
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// instructions. SIMD instructions can make code significantly
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// more performant.
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//
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// To see why, imagine we have a program in which we take the
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// square root of four (changing) f32 floats.
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//
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// A simple compiler would take the program and produce machine code
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// which calculates each square root sequentially. Most registers on
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// modern CPUs have 64 bits, so we could imagine that each float moves
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// into a 64-bit register, and the following happens four times:
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//
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// 32 bits 32 bits
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// +-------------------+
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// register | 0 | x |
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// +-------------------+
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//
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// |
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// [SQRT instruction]
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// V
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//
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// +-------------------+
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// | 0 | sqrt(x) |
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// +-------------------+
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//
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// Notice that half of the register contains blank data to which
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// nothing happened. What a waste! What if we were able to use
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// that space instead? This is the idea at the core of SIMD.
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//
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// Most modern CPUs contain specialized registers with at least 128 bits
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// for performing SIMD instructions. On a machine with 128-bit SIMD
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// registers, a smart compiler would probably NOT issue four sqrt
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// instructions as above, but instead pack the floats into a single
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// 128-bit register, then execute a single "packed" sqrt
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// instruction to do ALL the square root calculations at once.
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//
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// For example:
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//
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//
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// 32 bits 32 bits 32 bits 32 bits
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// +---------------------------------------+
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// register | 4.0 | 9.0 | 25.0 | 49.0 |
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// +---------------------------------------+
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//
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// |
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// [SIMD SQRT instruction]
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// V
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//
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// +---------------------------------------+
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// register | 2.0 | 3.0 | 5.0 | 7.0 |
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// +---------------------------------------+
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//
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// Pretty cool, right?
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//
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// Code with SIMD instructions is usually more performant than code
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// without SIMD instructions. Zig cares a lot about performance,
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// so it has built-in support for SIMD! It has a data structure that
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// directly supports SIMD instructions:
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//
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// +-----------+
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// | Vectors |
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// +-----------+
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//
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// Operations performed on vectors in Zig will be done in parallel using
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// SIMD instructions, whenever possible.
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//
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// Defining vectors in Zig is straightforwards. No library import is needed.
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const v1 = @Vector(3, i32){ 1, 10, 100 };
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const v2 = @Vector(3, f32){ 2.0, 3.0, 5.0 };
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// Vectors support the same builtin operators as their underlying base types.
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const v3 = v1 + v1; // { 2, 20, 200};
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const v4 = v2 * v2; // { 4.0, 9.0, 25.0};
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// Intrinsics that apply to base types usually extend to vectors.
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const v5: @Vector(3, f32) = @floatFromInt(v3); // { 2.0, 20.0, 200.0}
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const v6 = v4 - v5; // { 2.0, -11.0, -175.0}
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const v7 = @abs(v6); // { 2.0, 11.0, 175.0}
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// We can make constant vectors, and reduce vectors.
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const v8: @Vector(4, u8) = @splat(2); // { 2, 2, 2, 2}
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const v8_sum = @reduce(.Add, v8); // 8
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const v8_min = @reduce(.Min, v8); // 2
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// Fixed-length arrays can be automatically assigned to vectors (and vice-versa).
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const single_digit_primes = [4]i8{ 2, 3, 5, 7 };
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const prime_vector: @Vector(4, i8) = single_digit_primes;
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// Now let's use vectors to simplify and optimize some code!
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//
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// Ewa is writing a program in which they frequently want to compare
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// two lists of four f32s. Ewa expects the lists to be similar, and
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// wants to determine the largest pairwise difference between the lists.
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//
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// Ewa wrote the following function to figure this out.
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fn calcMaxPairwiseDiffOld(list1: [4]f32, list2: [4]f32) f32 {
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var max_diff: f32 = 0;
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for (list1, list2) |n1, n2| {
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const abs_diff = @abs(n1 - n2);
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if (abs_diff > max_diff) {
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max_diff = abs_diff;
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}
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}
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return max_diff;
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}
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// Ewa heard about vectors in Zig, and started writing a new vector
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// version of the function, but has got stuck!
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//
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// Help Ewa finish the vector version! The examples above should help.
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const Vec4 = @Vector(4, f32);
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fn calcMaxPairwiseDiffNew(a: Vec4, b: Vec4) f32 {
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const abs_diff_vec = ???;
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const max_diff = @reduce(???, abs_diff_vec);
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return max_diff;
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}
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// Quite the simplification! We could even write the function in one line
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// and it would still be readable.
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//
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// Since the entire function is now expressed in terms of vector operations,
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// the Zig compiler will easily be able to compile it down to machine code
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// which utilizes the all-powerful SIMD instructions and does a lot of the
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// computation in parallel.
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const std = @import("std");
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const print = std.debug.print;
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pub fn main() void {
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const l1 = [4]f32{ 3.141, 2.718, 0.577, 1.000 };
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const l2 = [4]f32{ 3.154, 2.707, 0.591, 0.993 };
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const mpd_old = calcMaxPairwiseDiffOld(l1, l2);
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const mpd_new = calcMaxPairwiseDiffNew(l1, l2);
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print("Max difference (old fn): {d: >5.3}\n", .{mpd_old});
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print("Max difference (new fn): {d: >5.3}\n", .{mpd_new});
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}
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@ -1,8 +1,8 @@
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--- exercises/058_quiz7.zig 2024-10-28 09:06:49.448505460 +0100
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+++ answers/058_quiz7.zig 2024-10-28 09:35:14.631932322 +0100
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--- exercises/058_quiz7.zig 2023-10-03 22:15:22.125574535 +0200
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+++ answers/058_quiz7.zig 2023-10-05 20:04:07.106101152 +0200
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@@ -192,8 +192,8 @@
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// Oops! The hermit forgot how to capture the union values
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// in a switch statement. Please capture each value as
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// in a switch statement. Please capture both values as
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// 'p' so the print statements work!
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- .place => print("{s}", .{p.name}),
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- .path => print("--{}->", .{p.dist}),
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@ -1,5 +1,5 @@
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--- exercises/065_builtins2.zig 2024-11-02 16:58:30.607829441 +0100
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+++ answers/065_builtins2.zig 2024-11-02 16:58:33.821220588 +0100
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--- exercises/065_builtins2.zig 2024-09-02 19:15:56.569952315 +0200
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+++ answers/065_builtins2.zig 2024-09-02 19:13:44.280600350 +0200
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@@ -58,7 +58,7 @@
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// Oops! We cannot leave the 'me' and 'myself' fields
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// undefined. Please set them here:
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@ -24,16 +24,16 @@
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// (which is a zero-bit type that takes up no space at all!):
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- if (fields[0].??? != void) {
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+ if (fields[0].type != void) {
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print(" {s}", .{fields[0].name});
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print(" {s}", .{@typeInfo(Narcissus).@"struct".fields[0].name});
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}
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- if (fields[1].??? != void) {
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+ if (fields[1].type != void) {
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print(" {s}", .{fields[1].name});
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print(" {s}", .{@typeInfo(Narcissus).@"struct".fields[1].name});
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}
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- if (fields[2].??? != void) {
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+ if (fields[2].type != void) {
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print(" {s}", .{fields[2].name});
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print(" {s}", .{@typeInfo(Narcissus).@"struct".fields[2].name});
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}
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@ -1,5 +1,5 @@
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--- exercises/099_formatting.zig 2024-11-07 21:45:10.459123650 +0100
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+++ answers/099_formatting.zig 2024-11-07 21:43:55.154345991 +0100
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--- exercises/099_formatting.zig 2023-10-03 22:15:22.125574535 +0200
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+++ answers/099_formatting.zig 2023-10-05 20:04:07.292771311 +0200
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@@ -131,7 +131,7 @@
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for (0..size) |b| {
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// What formatting is needed here to make our columns
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@ -1,13 +0,0 @@
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--- exercises/109_vectors.zig 2024-11-07 14:57:09.673383618 +0100
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+++ answers/109_vectors.zig 2024-11-07 14:22:59.069150138 +0100
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@@ -121,8 +121,8 @@
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const Vec4 = @Vector(4, f32);
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fn calcMaxPairwiseDiffNew(a: Vec4, b: Vec4) f32 {
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- const abs_diff_vec = ???;
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- const max_diff = @reduce(???, abs_diff_vec);
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+ const abs_diff_vec = @abs(a - b);
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+ const max_diff = @reduce(.Max, abs_diff_vec);
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return max_diff;
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}
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Loading…
Reference in a new issue