Import of the watch repository from Pebble

src/libutil/hexdump.c

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "util/hexdump.h"
+
+#include <stdio.h>
+#include <string.h>
+
+// offset + gap + 8 hex bytes + gap + 8 hex bytes + gap + 8 ascii bytes
+// + mini gap + 8 ascii bytes + null:
+#define LINE_BUFFER_LENGTH (4 + 2 + (3 * 8) + 2 + (3 * 8) + 2 + 8 + 1 + 8 + 1)
+
+void hexdump(const char *src_filename, int src_line_number, int level,
+             const uint8_t *data, size_t length, HexdumpLineCallback write_line_cb) {
+  char line_buffer[LINE_BUFFER_LENGTH];
+  unsigned int offset = 0;
+
+  while (offset < length) {
+    unsigned int buffer_offset = 0;
+
+    // Print data line offset
+    snprintf(line_buffer, LINE_BUFFER_LENGTH, "%04x  ", offset);
+    buffer_offset += 6;
+
+    // Print the hex bytes
+    const unsigned int num_line_bytes = ((length - offset) > 16) ? 16 : (length - offset);
+    for (unsigned int i = 0; i < num_line_bytes; ++i) {
+      if (i == 8) {
+        line_buffer[buffer_offset++] = ' ';
+      }
+
+      snprintf(line_buffer + buffer_offset, LINE_BUFFER_LENGTH - buffer_offset, "%02x ",
+               data[offset + i]);
+      buffer_offset += 3;
+    }
+
+    // Calculate and apply padding between the hex dump and the ascii dump.
+    unsigned int required_padding = 2;
+    if (num_line_bytes < 16) {
+      // If we're printing a partial line, pad out the rest so the
+      // ascii lines up.
+      required_padding += (16 - num_line_bytes) * 3;
+      if (num_line_bytes <= 8)
+      {
+        // Account for the gap between the 8 byte hex blocks.
+        required_padding += 1;
+      }
+    }
+
+    memset(line_buffer + buffer_offset, ' ', required_padding);
+    buffer_offset += required_padding;
+
+    // Print the ASCII bytes
+    for (unsigned int i = 0; i < num_line_bytes; ++i) {
+      if (i == 8)
+      {
+        line_buffer[buffer_offset++] = ' ';
+      }
+
+      char c = data[offset + i];
+      if (c < 32 || c > 126 || c == '`') // ` is used for log hash string delimiting
+      {
+        c = '.';
+      }
+      line_buffer[buffer_offset++] = c;
+    }
+
+    // No need to pad after a partial ascii line, since we don't line up
+    // anything after it.
+
+    // Null terminate and print.
+    line_buffer[buffer_offset] = 0;
+    write_line_cb(level, src_filename, src_line_number, line_buffer);
+
+    offset += 16;
+  }
+}