commit 84024fb05a3fd3df614711e4932ff97d763458fc
Author: Philippe PITTOLI <karchnu@karchnu.fr>
Date:   Fri Jun 21 01:07:12 2024 +0200

    Libhexa: first commit.

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..880cd5d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+zig-out
+.zig-cache
diff --git a/build.zig b/build.zig
new file mode 100644
index 0000000..57ef894
--- /dev/null
+++ b/build.zig
@@ -0,0 +1,112 @@
+const std = @import("std");
+
+const VERSION = "0.1.0";
+
+// Although this function looks imperative, note that its job is to
+// declaratively construct a build graph that will be executed by an external
+// runner.
+pub fn build(b: *std.Build) void {
+    // Standard target options allows the person running `zig build` to choose
+    // what target to build for. Here we do not override the defaults, which
+    // means any target is allowed, and the default is native. Other options
+    // for restricting supported target set are available.
+    const target = b.standardTargetOptions(.{});
+
+    // Standard optimization options allow the person running `zig build` to select
+    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
+    // set a preferred release mode, allowing the user to decide how to optimize.
+    const optimize = b.standardOptimizeOption(.{});
+
+    const static_lib = b.addStaticLibrary(.{
+        .name = "hexa",
+        // In this case the main source file is merely a path, however, in more
+        // complicated build scripts, this could be a generated file.
+        .root_source_file = b.path("src/bindings.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    // This declares intent for the library to be installed into the standard
+    // location when the user invokes the "install" step (the default step when
+    // running `zig build`).
+    b.installArtifact(static_lib);
+
+    const shared_lib = b.addSharedLibrary(.{
+        .name = "hexa",
+        .root_source_file = .{ .cwd_relative = "src/bindings.zig" },
+        .version = comptime (try std.SemanticVersion.parse(VERSION)),
+        .target = target,
+        .optimize = optimize,
+    });
+    shared_lib.linkLibC();
+    b.installArtifact(shared_lib);
+
+    const exe = b.addExecutable(.{
+        .name = "hexa",
+        .root_source_file = b.path("src/application.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    // This declares intent for the executable to be installed into the
+    // standard location when the user invokes the "install" step (the default
+    // step when running `zig build`).
+    b.installArtifact(exe);
+
+    // This *creates* a Run step in the build graph, to be executed when another
+    // step is evaluated that depends on it. The next line below will establish
+    // such a dependency.
+    const run_cmd = b.addRunArtifact(exe);
+
+    // By making the run step depend on the install step, it will be run from the
+    // installation directory rather than directly from within the cache directory.
+    // This is not necessary, however, if the application depends on other installed
+    // files, this ensures they will be present and in the expected location.
+    run_cmd.step.dependOn(b.getInstallStep());
+
+    // This allows the user to pass arguments to the application in the build
+    // command itself, like this: `zig build run -- arg1 arg2 etc`
+    if (b.args) |args| {
+        run_cmd.addArgs(args);
+    }
+
+    // This creates a build step. It will be visible in the `zig build --help` menu,
+    // and can be selected like this: `zig build run`
+    // This will evaluate the `run` step rather than the default, which is "install".
+    const run_step = b.step("run", "Run the app");
+    run_step.dependOn(&run_cmd.step);
+
+    // Creates a step for unit testing. This only builds the test executable
+    // but does not run it.
+    const lib_unit_tests = b.addTest(.{
+        .root_source_file = b.path("src/root.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    const run_lib_unit_tests = b.addRunArtifact(lib_unit_tests);
+
+    const exe_unit_tests = b.addTest(.{
+        .root_source_file = b.path("src/main.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);
+
+    // Similar to creating the run step earlier, this exposes a `test` step to
+    // the `zig build --help` menu, providing a way for the user to request
+    // running the unit tests.
+    const test_step = b.step("test", "Run unit tests");
+    test_step.dependOn(&run_lib_unit_tests.step);
+    test_step.dependOn(&run_exe_unit_tests.step);
+
+    const install_static_lib = b.addInstallArtifact(static_lib, .{});
+    const static_lib_step = b.step("static", "Compile LibIPC as a static library.");
+    static_lib_step.dependOn(&install_static_lib.step);
+
+    const install_shared_lib = b.addInstallArtifact(shared_lib, .{});
+    // b.getInstallStep().dependOn(&install_shared_lib.step);
+    const shared_lib_step = b.step("shared", "Compile LibIPC as a shared library.");
+    shared_lib_step.dependOn(&install_shared_lib.step);
+}
diff --git a/build.zig.zon b/build.zig.zon
new file mode 100644
index 0000000..cb5bccd
--- /dev/null
+++ b/build.zig.zon
@@ -0,0 +1,72 @@
+.{
+    // This is the default name used by packages depending on this one. For
+    // example, when a user runs `zig fetch --save <url>`, this field is used
+    // as the key in the `dependencies` table. Although the user can choose a
+    // different name, most users will stick with this provided value.
+    //
+    // It is redundant to include "zig" in this name because it is already
+    // within the Zig package namespace.
+    .name = "libhexa",
+
+    // This is a [Semantic Version](https://semver.org/).
+    // In a future version of Zig it will be used for package deduplication.
+    .version = "0.0.0",
+
+    // This field is optional.
+    // This is currently advisory only; Zig does not yet do anything
+    // with this value.
+    //.minimum_zig_version = "0.11.0",
+
+    // This field is optional.
+    // Each dependency must either provide a `url` and `hash`, or a `path`.
+    // `zig build --fetch` can be used to fetch all dependencies of a package, recursively.
+    // Once all dependencies are fetched, `zig build` no longer requires
+    // internet connectivity.
+    .dependencies = .{
+        // See `zig fetch --save <url>` for a command-line interface for adding dependencies.
+        //.example = .{
+        //    // When updating this field to a new URL, be sure to delete the corresponding
+        //    // `hash`, otherwise you are communicating that you expect to find the old hash at
+        //    // the new URL.
+        //    .url = "https://example.com/foo.tar.gz",
+        //
+        //    // This is computed from the file contents of the directory of files that is
+        //    // obtained after fetching `url` and applying the inclusion rules given by
+        //    // `paths`.
+        //    //
+        //    // This field is the source of truth; packages do not come from a `url`; they
+        //    // come from a `hash`. `url` is just one of many possible mirrors for how to
+        //    // obtain a package matching this `hash`.
+        //    //
+        //    // Uses the [multihash](https://multiformats.io/multihash/) format.
+        //    .hash = "...",
+        //
+        //    // When this is provided, the package is found in a directory relative to the
+        //    // build root. In this case the package's hash is irrelevant and therefore not
+        //    // computed. This field and `url` are mutually exclusive.
+        //    .path = "foo",
+
+        //    // When this is set to `true`, a package is declared to be lazily
+        //    // fetched. This makes the dependency only get fetched if it is
+        //    // actually used.
+        //    .lazy = false,
+        //},
+    },
+
+    // Specifies the set of files and directories that are included in this package.
+    // Only files and directories listed here are included in the `hash` that
+    // is computed for this package. Only files listed here will remain on disk
+    // when using the zig package manager. As a rule of thumb, one should list
+    // files required for compilation plus any license(s).
+    // Paths are relative to the build root. Use the empty string (`""`) to refer to
+    // the build root itself.
+    // A directory listed here means that all files within, recursively, are included.
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "src",
+        // For example...
+        //"LICENSE",
+        //"README.md",
+    },
+}
diff --git a/c-example/example.c b/c-example/example.c
new file mode 100644
index 0000000..474f54d
--- /dev/null
+++ b/c-example/example.c
@@ -0,0 +1,25 @@
+#include "../libhexa.h"
+
+#include <stdio.h>
+#include <string.h>
+
+#define BUFFER_SIZE 2000
+
+int main(void)
+{
+	char buffer[BUFFER_SIZE];
+	char inp[] = "hello this is me, how are you?";
+	char title[] = "this is my title";
+
+	uint32_t bufsize = BUFFER_SIZE;
+	uint32_t *bufsizep = &bufsize;
+
+	const int ret = hexdump(title, strlen(title), inp, strlen(inp), buffer, bufsizep);
+	if(ret != 0) {
+		printf("something bad happened\n");
+		return 1;
+	}
+
+	printf("%.*s", bufsize, buffer);
+	return 0;
+}
diff --git a/libhexa.h b/libhexa.h
new file mode 100644
index 0000000..ca55846
--- /dev/null
+++ b/libhexa.h
@@ -0,0 +1,13 @@
+#ifndef __LIBHEXA__
+#define __LIBHEXA__
+
+#include <stdint.h>
+
+// Write an hexadecimal dump of input data in the output buffer.
+// A title can be given to the dump, center-aligned on the first line.
+// In case the title is empty, this line won't be written at all.
+int32_t hexdump(char* title, uint32_t title_len
+	, char* input_buffer, uint32_t input_buffer_len
+	, char* output_buffer, unsigned int* output_buffer_len);
+
+#endif
diff --git a/makefile b/makefile
new file mode 100644
index 0000000..eaf953f
--- /dev/null
+++ b/makefile
@@ -0,0 +1,10 @@
+all: build
+
+build:
+	zig build
+
+build-test: build
+	gcc -o example c-example/example.c -L ./zig-out/lib/ -lhexa
+
+run-test: build
+	LD_LIBRARY_PATH=./zig-out/lib/ ./example
diff --git a/src/application.zig b/src/application.zig
new file mode 100644
index 0000000..c15cd69
--- /dev/null
+++ b/src/application.zig
@@ -0,0 +1,42 @@
+const std = @import("std");
+const hexa = @import("./libhexa.zig");
+const stdin  = std.io.getStdIn().reader();
+const stdout = std.io.getStdOut().writer();
+
+const line_size = 16;
+const nlines = 32;
+
+/// Print some bytes' hexdump on standard output.
+pub fn print_hex(title: []const u8, buffer : []const u8) !void
+{
+    var hexbuf: [line_size*nlines*10]u8 = undefined;
+    var hexfbs = std.io.fixedBufferStream(&hexbuf);
+    const hexwriter = hexfbs.writer();
+    try hexa.hexdump(hexwriter, title, buffer);
+    try stdout.print("{s}", .{hexfbs.getWritten()});
+}
+
+/// The program is simple: print an hexadecimal dump of input.
+/// Provided parameter will be shown as a title.
+pub fn main() !void
+{
+    var title : []const u8 = "";
+
+    const args = try std.process.argsAlloc(std.heap.page_allocator);
+    if (args.len > 2) {
+        try stdout.print("usage: {s} [title]\n", .{args[0]});
+        try stdout.print("example: {s} 'debug hexdump of blah'\n", .{args[0]});
+        return;
+    }
+
+    if (args.len == 2) { title = args[1]; }
+
+    var input_buffer: [line_size*nlines]u8 = undefined;
+    var n : u64 = undefined;
+    n = try stdin.read(&input_buffer);
+    while(n > 0)
+    {
+        try print_hex(title, input_buffer[0..n]);
+        n = try stdin.read(&input_buffer);
+    }
+}
diff --git a/src/bindings.zig b/src/bindings.zig
new file mode 100644
index 0000000..07d2bff
--- /dev/null
+++ b/src/bindings.zig
@@ -0,0 +1,37 @@
+const std = @import("std");
+const hexa = @import("./libhexa.zig");
+
+const log = std.log.scoped(.libhexa);
+const stdout = std.io.getStdOut().writer();
+
+/// Write an hexdump of input data in an output buffer.
+export fn hexdump(title: [*]const u8, title_len: u32,
+                  input_buffer: [*]const u8, input_buffer_len: u32,
+                  output_buffer: [*]u8, output_buffer_len: *u32) callconv(.C) i32
+{
+    var hexfbs = std.io.fixedBufferStream(output_buffer[0..output_buffer_len.*]);
+    const writer_output = hexfbs.writer();
+    hexa.hexdump(writer_output, title[0..title_len], input_buffer[0..input_buffer_len]) catch |err| {
+        switch(err) {
+            error.DiskQuota => log.warn("error.DiskQuota", .{}),
+            error.FileTooBig => log.warn("error.FileTooBig", .{}),
+            error.InputOutput => log.warn("error.InputOutput", .{}),
+            error.NoSpaceLeft => log.warn("error.NoSpaceLeft", .{}),
+            error.DeviceBusy => log.warn("error.DeviceBusy", .{}),
+            error.InvalidArgument => log.warn("error.InvalidArgument", .{}),
+            error.AccessDenied => log.warn("error.AccessDenied", .{}),
+            error.BrokenPipe => log.warn("error.BrokenPipe", .{}),
+            error.SystemResources => log.warn("error.SystemResources", .{}),
+            error.OperationAborted => log.warn("error.OperationAborted", .{}),
+            error.NotOpenForWriting => log.warn("error.NotOpenForWriting", .{}),
+            error.LockViolation => log.warn("error.LockViolation", .{}),
+            error.WouldBlock => log.warn("error.WouldBlock", .{}),
+            error.ConnectionResetByPeer => log.warn("error.ConnectionResetByPeer", .{}),
+            error.Unexpected => log.warn("error.Unexpected", .{}),
+        }
+        return -1;
+    };
+
+    output_buffer_len.* = @intCast(hexfbs.pos);
+    return 0;
+}
diff --git a/src/libhexa.zig b/src/libhexa.zig
new file mode 100644
index 0000000..bd6137f
--- /dev/null
+++ b/src/libhexa.zig
@@ -0,0 +1,72 @@
+const std = @import("std");
+
+pub fn hexdump(stream: anytype, header: []const u8, buffer: []const u8) std.posix.WriteError!void
+{
+    // Print a header.
+    if (header.len > 0) {
+        var hdr: [64]u8 = undefined;
+        const offset: usize = (hdr.len / 2) - ((header.len / 2) - 1);
+
+        @memset(hdr[0..hdr.len], ' ');
+        std.mem.copyForwards(u8, hdr[offset..hdr.len], header);
+
+        try stream.writeAll(hdr[0..hdr.len]);
+        try stream.writeAll("\n");
+    }
+
+    var hexb: u32 = 0;
+    var ascii: [16]u8 = undefined;
+    // First line, first left side (simple number).
+    try stream.print("  {d:0>4}:  ", .{hexb});
+
+    // Loop on all values in the buffer (i from 0 to buffer.len).
+    var i: u32 = 0;
+    while (i < buffer.len) : (i += 1) {
+        // Print actual hexadecimal value.
+        try stream.print("{X:0>2} ", .{buffer[i]});
+
+        // What to print (simple ascii text, right side).
+        if (buffer[i] >= ' ' and buffer[i] <= '~') {
+            ascii[(i % 16)] = buffer[i];
+        } else {
+            ascii[(i % 16)] = '.';
+        }
+
+        // Next input is a multiple of 8 = extra space.
+        if ((i + 1) % 8 == 0) {
+            try stream.writeAll(" ");
+        }
+
+        // No next input: print the right amount of spaces.
+        if ((i + 1) == buffer.len) {
+            // Each line is 16 bytes to print, each byte takes 3 characters.
+            var missing_spaces = 3 * (15 - (i % 16));
+            // Missing an extra space if the current index % 16 is less than 7.
+            if ((i % 16) < 7) {
+                missing_spaces += 1;
+            }
+            while (missing_spaces > 0) : (missing_spaces -= 1) {
+                try stream.writeAll(" ");
+            }
+        }
+
+        // Every 16 bytes: print ascii text and line return.
+
+        // Case 1: it's been 16 bytes AND it's the last byte to print.
+        if ((i + 1) % 16 == 0 and (i + 1) == buffer.len) {
+            try stream.print("{s}\n", .{ascii[0..ascii.len]});
+        }
+        // Case 2: it's been 16 bytes but it's not the end of the buffer.
+        else if ((i + 1) % 16 == 0 and (i + 1) != buffer.len) {
+            try stream.print("{s}\n", .{ascii[0..ascii.len]});
+            hexb += 16;
+            try stream.print("  {d:0>4}:  ", .{hexb});
+        }
+        // Case 3: not the end of the 16 bytes row but it's the end of the buffer.
+        else if ((i + 1) % 16 != 0 and (i + 1) == buffer.len) {
+            try stream.print(" {s}\n", .{ascii[0..((i + 1) % 16)]});
+        }
+        // Case 4: not the end of the 16 bytes row and not the end of the buffer.
+        //         Do nothing.
+    }
+}