Merge branch 'dev' of github.com:lighttransport/tinyusdz into dev

CMakeLists.txt

@@ -376,6 +376,7 @@ set(TINYUSDZ_SOURCES
     ${PROJECT_SOURCE_DIR}/src/ascii-parser-timesamples.cc
     ${PROJECT_SOURCE_DIR}/src/ascii-parser-timesamples-array.cc
     ${PROJECT_SOURCE_DIR}/src/audio-loader.cc
+    ${PROJECT_SOURCE_DIR}/src/base122.cc
     ${PROJECT_SOURCE_DIR}/src/usda-reader.cc
     ${PROJECT_SOURCE_DIR}/src/usdc-reader.cc
     ${PROJECT_SOURCE_DIR}/src/usda-writer.cc

src/base122.cc

@@ -0,0 +1,66 @@
+#include "base122.hh"
+
+// Base122 uses 122 safe printable ASCII characters
+// Excluding problematic chars like quotes, backslash, DEL, etc.
+static const char base122_alphabet[122] = 
+    "!#$%&()*+,-./0123456789:;<=>?@"
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZ[]^_`"
+    "abcdefghijklmnopqrstuvwxyz{|}~"
+    "\xA1\xA2\xA3\xA4\xA5\xA6\xA7\xA8\xA9\xAA\xAB\xAC\xAD\xAE\xAF"
+    "\xB0\xB1\xB2\xB3\xB4\xB5\xB6\xB7\xB8\xB9\xBA\xBB\xBC\xBD\xBE";
+
+// Build decode map at startup
+static uint8_t base122_decode_map[256] = {0};
+static bool base122_decode_map_ready = false;
+static void base122_init_decode_map() {
+    if (base122_decode_map_ready) return;
+    for (int i = 0; i < 256; ++i) base122_decode_map[i] = 0xFF;
+    for (int i = 0; i < 122; ++i) base122_decode_map[static_cast<unsigned char>(base122_alphabet[i])] = static_cast<uint8_t>(i);
+    base122_decode_map_ready = true;
+}
+
+// Encode binary data to base122 string
+inline std::string base122_encode(const std::vector<uint8_t>& data) {
+    std::string out;
+    size_t i = 0;
+    while (i < data.size()) {
+        uint32_t val = 0;
+        int bytes = 0;
+        for (; bytes < 7 && i < data.size(); ++bytes, ++i) {
+            val |= static_cast<uint32_t>(data[i]) << (8 * bytes);
+        }
+        int chars = (bytes * 8 + 6) / 7;
+        for (int c = 0; c < chars; ++c) {
+            out += base122_alphabet[val % 122];
+            val /= 122;
+        }
+    }
+    return out;
+}
+
+// Decode base122 string to binary data
+// Returns 0 on success, nonzero on error (invalid char or truncated input)
+inline int base122_decode(const std::string& str, std::vector<uint8_t>& out) {
+    base122_init_decode_map();
+    out.clear();
+    size_t i = 0;
+    while (i < str.size()) {
+        uint32_t val = 0;
+        int chars = 0;
+        uint32_t mult = 1;
+        // Read up to 8 chars (max for 7 bytes)
+        for (; chars < 8 && i < str.size(); ++chars, ++i) {
+            uint8_t v = base122_decode_map[static_cast<unsigned char>(str[i])];
+            if (v == 0xFF) return 1; // Invalid char
+            val += v * mult;
+            mult *= 122;
+        }
+        // Output up to 7 bytes
+        for (int b = 0; b < 7; ++b) {
+            if (val == 0 && (i == str.size() || chars < b+1)) break;
+            out.push_back(static_cast<uint8_t>(val & 0xFF));
+            val >>= 8;
+        }
+    }
+    return 0;
+}

src/base122.hh

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <string>
+#include <vector>
+#include <cstdint>
+
+namespace tinyusdz {
+
+std::string base122_encode(const std::vector<uint8_t>& data);
+
+// Decode base122 string to binary data
+// Returns 0 on success, nonzero on error (invalid char or truncated input)
+int base122_decode(const std::string& str, std::vector<uint8_t>& out);
+
+
+} // namespace tinyusdz