From 63d75ec2804873496f9a73a8777dd298de416df3 Mon Sep 17 00:00:00 2001
From: neithanmo <neithanmo@gmail.com>
Date: Mon, 25 Nov 2024 19:43:51 +0100
Subject: [PATCH] Add function to convert u128 numbers to string

---
 app/src/constants.h | 17 +++++++++++++++
 app/src/ui_utils.c  | 53 +++++++++++++++++++++++++++++++++++++++++++++
 app/src/ui_utils.h  | 16 ++++++++++++++
 3 files changed, 86 insertions(+)

diff --git a/app/src/constants.h b/app/src/constants.h
index 0f59ee8..1a3ec6d 100644
--- a/app/src/constants.h
+++ b/app/src/constants.h
@@ -1,3 +1,20 @@
+/*******************************************************************************
+ *  (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
+
 // Common BECH32m constants
 #define CHECKSUM_LENGTH 8
 #define BECH32_BITS_PER_CHAR 5
diff --git a/app/src/ui_utils.c b/app/src/ui_utils.c
index 3fba8b7..2c131bb 100644
--- a/app/src/ui_utils.c
+++ b/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;
+}
diff --git a/app/src/ui_utils.h b/app/src/ui_utils.h
index 98c8b94..a91e382 100644
--- a/app/src/ui_utils.h
+++ b/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);