First Commit

.gitignore

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+.zig-cache
+zig-out

README.md

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+# SieveEratosthenes
+
+Sieve of Eratosthenes to find all 32-bit prime numbers in Zig. Uses the same algorithm as the [Java Version](https://github.com/WWelna/SieveEratosthenes).
+
+```
+wwelna@COINTEL-WORKSTATION:~/GitHub/SieveEratosthenes-zig$ zig build -Doptimize=ReleaseFast run
+```
+
+## License
+
+Copyright (C) 2025 William Welna (wwelna@occultusterra.com)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

build.zig

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+const std = @import("std");
+
+pub fn build(b: *std.Build) void {
+
+    const target = b.standardTargetOptions(.{});
+    const optimize = b.standardOptimizeOption(.{});
+    const exe = b.addExecutable(.{
+        .name = "SieveEratosthenes_zig",
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("src/main.zig"),
+            .target = target,
+            .optimize = optimize,
+            .imports = &.{
+            },
+        }),
+    });
+    exe.linkLibC();
+
+    b.installArtifact(exe);
+
+    const run_step = b.step("run", "Run the app");
+    const run_cmd = b.addRunArtifact(exe);
+
+    run_step.dependOn(&run_cmd.step);
+    run_cmd.step.dependOn(b.getInstallStep());
+
+    if (b.args) |args| {
+        run_cmd.addArgs(args);
+    }
+}

src/main.zig

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+// Copyright (C) 2025 William Welna (wwelna@occultusterra.com)
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+const std = @import("std");
+
+const max_num_32 = std.math.maxInt(u32);
+const max_u64_need_32 = ((max_num_32 / 8)/8);
+
+inline fn setBit(sieve:[]u64, i:usize) void {
+    sieve[i/64] |= @as(u64, 1) << @intCast(i % 64);
+}
+
+inline fn getBit(sieve:[]u64, i:usize) bool {
+    if(sieve[i/64] & @as(u64, 1) << @intCast(i % 64)>0) { 
+        return true;
+    } else return false;
+}
+
+inline fn writeToFile(sieve:[]u64) !void {
+    var buffer:[8096]u8 = undefined;
+    const file = try std.fs.cwd().createFile("SieveEratosthenes-Zig.bin", .{.truncate=true});
+    defer file.close();
+    var writer = file.writer(&buffer);
+
+    var x:usize = 2;
+    while (x <= max_num_32) : (x += 1) {
+        if(!getBit(sieve, x)) {
+            const bytes = std.mem.toBytes(std.mem.nativeToBig(u32, @as(u32, @truncate(x))));
+            _ = try writer.interface.write(&bytes);
+        }
+    }
+    try writer.interface.flush();
+}
+
+pub fn main() !void {
+    var arena = std.heap.ArenaAllocator.init(std.heap.c_allocator);
+    var allocator = arena.allocator();
+
+    var stdout_buffer: [1024]u8 = undefined;
+    var stdout_writer = std.fs.File.stdout().writer(&stdout_buffer);
+    const stdout = &stdout_writer.interface;
+
+    var sieve_32:[]u64 = undefined;
+    sieve_32 = try allocator.alloc(u64, max_u64_need_32); @memset(sieve_32, 0);
+
+    try stdout.print("Starting...\n", .{});
+    try stdout.flush();
+    var x:usize = 2;
+    while (x * x <= max_num_32) : (x += 1) {
+        if (!getBit(sieve_32, x)) {
+            var y:usize = x * x;
+            while (y <= max_num_32) : (y += x) {
+                setBit(sieve_32, y);
+            }
+        }
+    }
+
+    try stdout.print("Writing to file...\n", .{});
+    try stdout.flush();
+
+    try writeToFile(sieve_32);
+
+    try stdout.flush();
+    arena.deinit();
+}