From 7d44197aef7cfc063329f2cdcc742d4d1c76af2d Mon Sep 17 00:00:00 2001
From: Tilen Majerle <tilen@majerle.eu>
Date: Fri, 30 Aug 2024 10:54:45 +0200
Subject: [PATCH] Simplify output generator for integer

---
 dev/main.c                       |  5 +++-
 lwprintf/src/lwprintf/lwprintf.c | 39 +++++++++++++++-----------------
 2 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/dev/main.c b/dev/main.c
index a466bbe..0bf56fa 100644
--- a/dev/main.c
+++ b/dev/main.c
@@ -26,7 +26,6 @@ size_t tests_passed, tests_failed;
 
 #define do_test(buff_ptr, buff_size, exp_out, exp_out_len, fmt, ...)                                                   \
     do {                                                                                                               \
-        char my_buffer[1234];                                                                                          \
         int len = lwprintf_snprintf((buff_ptr), (buff_size), (fmt), ##__VA_ARGS__);                                    \
         if (len != (exp_out_len)) {                                                                                    \
             printf("Test error on line: %d\r\n", __LINE__);                                                            \
@@ -120,6 +119,10 @@ main(void) {
     do_test(buffer, sizeof(buffer), "1.234560e-09", 12, "%e", 0.00000000123456);
     do_test(buffer, sizeof(buffer), "-000000000001.2346e-01", 22, "%022.4e", -0.123456);
     do_test(buffer, sizeof(buffer), "-1.2346E+02", 11, "%.4E", -123.456);
+    do_test(buffer, sizeof(buffer), "0", 1, "%d", 0);
+    do_test(buffer, sizeof(buffer), "1", 1, "%d", 1);
+    do_test(buffer, sizeof(buffer), "10", 2, "%d", 10);
+    do_test(buffer, sizeof(buffer), "140", 3, "%d", 140);
     do_test(buffer, sizeof(buffer), " 28", 3, "% 3u", (unsigned)28);
     do_test(buffer, sizeof(buffer), "028", 3, "%03d", 28);
     do_test(buffer, sizeof(buffer), "+28", 3, "%+03d", 28);
diff --git a/lwprintf/src/lwprintf/lwprintf.c b/lwprintf/src/lwprintf/lwprintf.c
index 3894653..7632a2c 100644
--- a/lwprintf/src/lwprintf/lwprintf.c
+++ b/lwprintf/src/lwprintf/lwprintf.c
@@ -359,30 +359,27 @@ prv_out_str(lwprintf_int_t* lwi, const char* buff, size_t buff_size) {
  */
 static int
 prv_longest_unsigned_int_to_str(lwprintf_int_t* lwi, uint_maxtype_t num) {
-    uint_maxtype_t den, digit;
-    uint8_t digits_cnt;
-    char chr;
+    /* Start with digits length, support binary with int, that is 32-bits maximum width */
+    char num_buf[33], *num_buf_ptr = &num_buf[sizeof(num_buf)];
 
     /* Check if number is zero */
-    lwi->m.flags.is_num_zero = (num) == 0;
-    if ((num) == 0) {
-        prv_out_str_before(lwi, 1);
-        lwi->out_fn(lwi, '0');
-        prv_out_str_after(lwi, 1);
-    } else { /* Start with digits length */
-        for (digits_cnt = 0, den = (num); den > 0; ++digits_cnt, den /= lwi->m.base) {}
-        for (den = 1; ((num) / den) >= lwi->m.base; den *= lwi->m.base) {}
-
-        prv_out_str_before(lwi, digits_cnt);
-        for (; den > 0;) {
-            digit = (num) / den;
-            (num) = (num) % den;
-            den = den / lwi->m.base;
-            chr = (char)digit + (char)(digit >= 10 ? ((lwi->m.flags.uc ? 'A' : 'a') - 10) : '0');
-            lwi->out_fn(lwi, chr);
-        }
-        prv_out_str_after(lwi, digits_cnt);
+    lwi->m.flags.is_num_zero = num == 0;
+
+    /* Fill the buffer backward */
+    *--num_buf_ptr = '\0';
+    do {
+        int digit = num % lwi->m.base;
+        num /= lwi->m.base;
+        *--num_buf_ptr = (char)digit + (char)(digit >= 10 ? ((lwi->m.flags.uc ? 'A' : 'a') - 10) : '0');
+    } while (num > 0);
+
+    /* Calculate and generate the output */
+    size_t len = sizeof(num_buf) - (size_t)((uintptr_t)num_buf_ptr - (uintptr_t)num_buf) - 1;
+    prv_out_str_before(lwi, len);
+    for (; *num_buf_ptr;) {
+        lwi->out_fn(lwi, *num_buf_ptr++);
     }
+    prv_out_str_after(lwi, len);
     return 1;
 }