From 602a7525d23e85b8cae0911bc1cec98b2cc5659c Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Sat, 16 Sep 2023 17:09:55 -0400
Subject: [PATCH] Add %p format specifier for printing pointers

---
 src/hulk/writef.d | 39 +++++++++++++++++++++++++++------------
 1 file changed, 27 insertions(+), 12 deletions(-)

diff --git a/src/hulk/writef.d b/src/hulk/writef.d
index 6ef633e..d39d1ec 100644
--- a/src/hulk/writef.d
+++ b/src/hulk/writef.d
@@ -34,18 +34,25 @@ size_t writef(string s, va_list args, ch_out_fn ch_out)
                 length_written++;
                 escape = false;
             }
+            else if (c == 'p')
+            {
+                ulong v;
+                va_arg(args, v);
+                length_written += write_hex(v, true, true, pad, width, ch_out);
+                escape = false;
+            }
             else if (c == 'x')
             {
                 ulong v;
                 va_arg(args, v);
-                length_written += write_hex(v, false, pad, width, ch_out);
+                length_written += write_hex(v, false, false, pad, width, ch_out);
                 escape = false;
             }
             else if (c == 'X')
             {
                 ulong v;
                 va_arg(args, v);
-                length_written += write_hex(v, true, pad, width, ch_out);
+                length_written += write_hex(v, true, false, pad, width, ch_out);
                 escape = false;
             }
             else if (c == 'u')
@@ -88,27 +95,35 @@ size_t writef(string s, va_list args, ch_out_fn ch_out)
  *
  * @param v Value to format.
  * @param upper Whether to use uppercase letters.
+ * @param pointer Whether to format as a pointer.
  * @param pad Pad character to use.
  * @param width Field width.
  * @param ch_out Character output function.
  *
  * @return Number of characters written.
  */
-private size_t write_hex(ulong v, bool upper, char pad, size_t width, ch_out_fn ch_out)
+private size_t write_hex(ulong v, bool upper, bool pointer, char pad, size_t width, ch_out_fn ch_out)
 {
     static __gshared const(char)[16] hex_chars_lower = "0123456789abcdef";
     static __gshared const(char)[16] hex_chars_upper = "0123456789ABCDEF";
-    char[16] buf;
-    size_t i;
+    char[19] buf;
+    size_t digit;
+    size_t buf_idx;
     do
     {
         ulong n = v & 0xFu;
-        buf[i] = upper ? hex_chars_upper[n] : hex_chars_lower[n];
+        buf[buf_idx] = upper ? hex_chars_upper[n] : hex_chars_lower[n];
         v >>= 4u;
-        i++;
+        buf_idx++;
+        digit++;
+        if (pointer && ((digit % 4) == 0) && (v != 0u))
+        {
+            buf[buf_idx] = '_';
+            buf_idx++;
+        }
     } while (v != 0u);
-    size_t length_written = i;
-    while (width > i)
+    size_t length_written = buf_idx;
+    while (width > buf_idx)
     {
         ch_out(pad);
         width--;
@@ -116,9 +131,9 @@ private size_t write_hex(ulong v, bool upper, char pad, size_t width, ch_out_fn
     }
     do
     {
-        i--;
-        ch_out(buf[i]);
-    } while (i != 0u);
+        buf_idx--;
+        ch_out(buf[buf_idx]);
+    } while (buf_idx != 0u);
     return length_written;
 }