util:hex-dumper

util/BUILD

@@ -92,6 +92,29 @@ cc_test(
     ],
 )
 
+cc_library(
+    name = "hex-dumper",
+    srcs = ["hex-dumper.cc"],
+    hdrs = ["hex-dumper.h"],
+    deps = [
+        "//base:types",
+        "//io:file",
+        "//io:file-utils",
+        "@com_google_absl//absl/container:fixed_array",
+    ],
+)
+
+cc_test(
+    name = "hex-dumper_test",
+    srcs = ["hex-dumper_test.cc"],
+    deps = [
+        ":hex-dumper",
+        "//base:types",
+        "//io:memory-file",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
 cc_library(
     name = "pod",
     hdrs = ["pod.h"],

util/hex-dumper.cc

@@ -0,0 +1,73 @@
+#include "util/hex-dumper.h"
+
+#include <algorithm>
+
+#include "io/file-utils.h"
+
+namespace util {
+namespace {
+
+inline char to_hex(int value) {
+    return value < 10 ? '0' + value : 'a' + value - 10;
+}
+
+inline char to_char(int value) {
+    return value >= 32 && value <= 127 ? value : '.';
+}
+
+void put_uint8_hex(uint8_t value, char output[2]) {
+    output[0] = to_hex(value >> 4);
+    output[1] = to_hex(value & 0xf);
+}
+
+void put_uint32_hex(uint32_t value, char output[8]) {
+    for (int i = 0; i < 8; ++i) {
+        output[i] = to_hex(value >> 28);
+        value <<= 4;
+    }
+}
+
+}  // namespace
+
+HexDumper::HexDumper(int width)
+    : width_(width),
+      buffer_(char_start() + width_ + 1, ' ') {}
+
+std::error_code HexDumper::dump(
+    uint32_t offset, ConstBufferSpan input, io::File &output) {
+    while (input.size() >= width_) {
+        std::error_code ec = dump_line(offset, input, output);
+        if (ec) {
+            return ec;
+        }
+        offset += width_;
+        input.remove_prefix(width_);
+    }
+    if (!input.empty()) {
+        std::error_code ec = dump_line(offset, input, output);
+        if (ec) {
+            return ec;
+        }
+    }
+    return {};
+}
+
+std::error_code HexDumper::dump_line(
+    uint32_t offset, ConstBufferSpan input, io::File &output) {
+    put_uint32_hex(offset, &buffer_[0]);
+    buffer_[8] = ':';
+    const size_t size = std::min(input.size(), width_);
+    size_t i;
+    for (i = 0; i < size; ++i) {
+        put_uint8_hex(input[i], &buffer_[i * 5 / 2 + 10]);
+        buffer_[char_start() + i] = to_char(input[i]);
+    }
+    for (; i < width_; ++i) {
+        buffer_[i * 5 / 2 + 10] = ' ';
+        buffer_[i * 5 / 2 + 11] = ' ';
+    }
+    buffer_[char_start() + size] = '\n';
+    return io::write(output, {buffer_.data(), char_start() + size + 1});
+}
+
+}  // namespace util

util/hex-dumper.h

@@ -0,0 +1,32 @@
+#ifndef _UTIL_HEX_DUMPER_H
+#define _UTIL_HEX_DUMPER_H
+
+#include <cstddef>
+#include <cstdint>
+#include <system_error>
+
+#include "absl/container/fixed_array.h"
+#include "base/types.h"
+#include "io/file.h"
+
+namespace util {
+
+class HexDumper {
+public:
+    explicit HexDumper(int width = 16);
+
+    std::error_code dump(
+        uint32_t offset, ConstBufferSpan input, io::File &output);
+    std::error_code dump_line(
+        uint32_t offset, ConstBufferSpan input, io::File &output);
+
+private:
+    size_t char_start() const { return (width_ * 5 + 23) / 2; }
+
+    const size_t width_;
+    absl::FixedArray<char, 80> buffer_;
+};
+
+}  // namespace util
+
+#endif  // _UTIL_HEX_DUMPER_H

util/hex-dumper_test.cc

@@ -0,0 +1,23 @@
+#include "util/hex-dumper.h"
+
+#include <string_view>
+#include <system_error>
+#include <gtest/gtest.h>
+
+#include "base/types.h"
+#include "io/memory-file.h"
+
+namespace util {
+namespace {
+
+TEST(DumpHexTest, basic) {
+    HexDumper dumper(7);
+    io::MemoryFile file;
+    EXPECT_EQ(dumper.dump(12, "hello world\n", file), std::error_code());
+    EXPECT_EQ(std::string_view(ConstBufferSpan(file.content())),
+              "0000000c: 6865 6c6c 6f20 77  hello w\n"
+              "00000013: 6f72 6c64 0a       orld.\n");
+}
+
+}  // namespace
+}  // namespace util