From f63a33884f411e312d7ad59195f3887dff87990e Mon Sep 17 00:00:00 2001
From: Calvin Rose <calsrose@gmail.com>
Date: Thu, 30 Jan 2025 07:36:18 -0600
Subject: [PATCH] Add hexfloats - Address #1550

---
 src/core/strtod.c      | 12 ++++++++++--
 test/suite-parse.janet |  3 +++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/core/strtod.c b/src/core/strtod.c
index 67247aa6..17fbc450 100644
--- a/src/core/strtod.c
+++ b/src/core/strtod.c
@@ -298,8 +298,10 @@ int janet_scan_number_base(
     }
 
     /* If still base is 0, set to default (10) */
+    int exp_base = base;
     if (base == 0) {
         base = 10;
+        exp_base = 10;
     }
 
     /* Skip leading zeros */
@@ -322,6 +324,12 @@ int janet_scan_number_base(
         } else if (*str == '&') {
             foundexp = 1;
             break;
+        } else if (base == 16 && (*str == 'P' || *str == 'p')) { /* IEEE hex float */
+            foundexp = 1;
+            exp_base = 10;
+            base = 2;
+            ex *= 4; /* We need to correct the current exponent after we change the base */
+            break;
         } else if (base == 10 && (*str == 'E' || *str == 'e')) {
             foundexp = 1;
             break;
@@ -360,9 +368,9 @@ int janet_scan_number_base(
         }
         while (str < end) {
             int digit = digit_lookup[*str & 0x7F];
-            if (*str > 127 || digit >= base) goto error;
+            if (*str > 127 || digit >= exp_base) goto error;
             if (ee < (INT32_MAX / 40)) {
-                ee = base * ee + digit;
+                ee = exp_base * ee + digit;
             }
             str++;
             seenadigit = 1;
diff --git a/test/suite-parse.janet b/test/suite-parse.janet
index 05b34292..08e8a993 100644
--- a/test/suite-parse.janet
+++ b/test/suite-parse.janet
@@ -208,5 +208,8 @@
 (parser/consume p `")`)
 (assert (= (parser/produce p) ["hello"]))
 
+# Hex floats
+(assert (= math/pi +0x1.921fb54442d18p+0001))
+
 (end-suite)