Add function to convert u128 numbers to string

app/src/constants.h

@@ -1,3 +1,23 @@
+/*******************************************************************************
+ *  (c) 2018 - 2023 Zondax AG
+ *
+ *  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.
+ ********************************************************************************/
+#define U128_STR_MAX_LEN 40
+
+// raw address len before encoding
+#define ADDRESS_LEN_BYTES 80
+
 // Common BECH32m constants
 #define CHECKSUM_LENGTH 8
 #define BECH32_BITS_PER_CHAR 5
@@ -22,3 +42,13 @@
 #define ENCODED_ADDR_LEN (ADDR_HRP_LENGTH + SEPARATOR_LENGTH + ENCODED_DATA_LENGTH)
 
 #define ENCODED_ADDR_BUFFER_SIZE (ENCODED_ADDR_LEN + 2)
+
+
+// MEMO transaction constants
+#define MEMO_CIPHERTEXT_LEN_BYTES 528
+
+// This is the `MEMO_CIPHERTEXT_LEN_BYTES` - MAC size (16 bytes).
+#define MEMO_LEN_BYTES 512
+
+// This is the largest text length we can support
+#define MAX_TEXT_LEN MEMO_LEN_BYTES - ADDRESS_LEN_BYTES

app/src/keys_def.h

@@ -32,9 +32,6 @@ extern "C" {
 #define INCOMING_VIEWING_KEY_LEN KEY_LEN     // Assuming modulo r size
 #define ADDR_MAX_ENC_LEN 150                 // The maximun length of the encoded address
 
-// raw address len before encoding
-#define ADDRESS_LEN_BYTES 80
-
 /// Number of bits in the address short form divided by the number of bits per Bech32m character
 #define ADDRESS_NUM_CHARS_SHORT_FORM 24
 

app/src/ui_utils.c

@@ -63,3 +63,56 @@ parser_error_t printAssetId(uint8_t *asset, uint16_t asset_len, char *out, uint1
                               asset, asset_len, ASSET_ID_LEN,
                               out, out_len);
 }
+
+parser_error_t uint128_to_str(char *data, int dataLen, uint64_t high, uint64_t low) {
+    if (data == NULL) return parser_no_data;
+    if (dataLen < U128_STR_MAX_LEN) return parser_value_out_of_range;
+
+    MEMZERO(data, dataLen);
+    char *p = data;
+
+    if (high == 0 && low == 0) {
+        *(p++) = '0';
+        return parser_ok;
+    }
+
+    uint64_t temp_high = high;
+    uint64_t temp_low = low;
+
+    while (temp_high != 0 || temp_low != 0) {
+        if (p - data >= (dataLen - 1)) return parser_value_out_of_range;
+
+        uint64_t quotient_high = 0;
+        uint64_t quotient_low = 0;
+        uint64_t remainder = 0;
+        uint64_t current;
+
+        current = temp_high;
+        quotient_high = current / 10;
+        remainder = current % 10;
+
+        current = (remainder << 32) | (temp_low >> 32);
+        uint64_t q = current / 10;
+        remainder = current % 10;
+        quotient_low = (q << 32);
+
+        current = (remainder << 32) | (temp_low & 0xFFFFFFFF);
+        q = current / 10;
+        remainder = current % 10;
+        quotient_low |= q;
+
+        *(p++) = (char)('0' + remainder);
+        temp_high = quotient_high;
+        temp_low = quotient_low;
+    }
+
+    while (p > data) {
+        p--;
+        char z = *data;
+        *data = *p;
+        *p = z;
+        data++;
+    }
+
+    return parser_ok;
+}

app/src/ui_utils.h

@@ -41,3 +41,19 @@ parser_error_t printBech32Encoded(const char *prefix, uint16_t prefix_len, uint8
 
 parser_error_t printAddress(uint8_t *address, uint16_t address_len, char *out, uint16_t out_len);
 parser_error_t printAssetId(uint8_t *asset, uint16_t asset_len, char *out, uint16_t out_len);
+
+/**
+ * Converts a 128-bit unsigned integer to its decimal string representation.
+ * Output buffer will be null terminated and cleared using MEMZERO.
+ *
+ * @param[out] data    Output buffer for the resulting string
+ * @param[in]  dataLen Size of the output buffer
+ * @param[in]  high    Upper 64 bits of the 128-bit number
+ * @param[in]  low     Lower 64 bits of the 128-bit number
+ *
+ * @return parser_error_t:
+ *         - parser_ok on success
+ *         - parser_no_data if data is NULL
+ *         - parser_value_out_of_range if buffer too small (< U128_STR_MAX_LEN)
+ */
+parser_error_t uint128_to_str(char *data, int dataLen, uint64_t high, uint64_t low);