From c925aaceb24fd431c8deec6675c02c9819296f8c Mon Sep 17 00:00:00 2001
From: Emanuel Sprung <emanuel.sprung@gmail.com>
Date: Tue, 31 Mar 2020 00:40:22 +0200
Subject: [PATCH] AK: Print double numbers with printf

This patchset allows double numbers to be printed with the printf function.
The fraction will always be printed as 6 digit number. This can be improved :^)
---
 AK/PrintfImplementation.h | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/AK/PrintfImplementation.h b/AK/PrintfImplementation.h
index 34a7c7106a..cab0e735b5 100644
--- a/AK/PrintfImplementation.h
+++ b/AK/PrintfImplementation.h
@@ -177,6 +177,26 @@ template<typename PutChFunc>
     return fieldWidth;
 }
 
+template<typename PutChFunc>
+[[gnu::always_inline]] inline int print_double(PutChFunc putch, char*& bufptr, double number, bool leftPad, bool zeroPad, u32 fieldWidth)
+{
+    int length = 0;
+
+    if (number < 0) {
+        putch(bufptr, '-');
+        length++;
+        number = 0 - number;
+    }
+
+    length = print_u64(putch, bufptr, (i64)number, leftPad, zeroPad, fieldWidth);
+    putch(bufptr, '.');
+    length++;
+    double fraction = number - (i64)number;
+    // FIXME: Allow other fractions
+    fraction = fraction * 1000000;
+    return length + print_u64(putch, bufptr, (i64)fraction, leftPad, true, 6);
+}
+
 template<typename PutChFunc>
 [[gnu::always_inline]] inline int print_i64(PutChFunc putch, char*& bufptr, i64 number, bool leftPad, bool zeroPad, u32 fieldWidth)
 {
@@ -361,8 +381,7 @@ template<typename PutChFunc>
 #if !defined(BOOTSTRAPPER) && !defined(KERNEL)
             case 'g':
             case 'f':
-                // FIXME: Print as float!
-                ret += print_i64(putch, bufptr, (u64)va_arg(ap, double), left_pad, zeroPad, fieldWidth);
+                ret += print_double(putch, bufptr, va_arg(ap, double), left_pad, zeroPad, fieldWidth);
                 break;
 #endif