From a9383f64418867b5b69f792dd71db532559df63c Mon Sep 17 00:00:00 2001
From: JackChen <17683835261@163.com>
Date: Tue, 10 Feb 2026 09:27:09 +0800
Subject: [PATCH 1/4] time-difference

---
 goldfish/srfi/srfi-19.scm         | 31 +++++++++++++++++-
 tests/goldfish/liii/time-test.scm | 53 +++++++++++++++++++++++++++++++
 2 files changed, 83 insertions(+), 1 deletion(-)

diff --git a/goldfish/srfi/srfi-19.scm b/goldfish/srfi/srfi-19.scm
index 8ccbe89e..9272b992 100644
--- a/goldfish/srfi/srfi-19.scm
+++ b/goldfish/srfi/srfi-19.scm
@@ -66,6 +66,7 @@
     copy-time
     ;; Time comparison procedures
     ;; Time arithmetic procedures
+    time-difference
     ;; Current time and clock resolution
     current-date current-julian-day current-time time-resolution
     ;; Date object and accessors
@@ -155,7 +156,35 @@
     ;; Time arithmetic procedures
     ;; ====================
 
-    ;; TODO
+    (define (priv:time->nanoseconds time)
+      (+ (* (time-second time) priv:NANO)
+         (time-nanosecond time)))
+
+    (define (priv:nanoseconds->values nanoseconds)
+      (receive (sec ns) (floor/ nanoseconds priv:NANO)
+        (values ns sec)))
+
+    (define (priv:time-difference time1 time2 time3)
+      (unless (and (time? time1) (time? time2))
+        (error 'wrong-type-arg "time-difference: time1 and time2 must be time objects" (list time1 time2)))
+      (unless (eq? (time-type time1) (time-type time2))
+        (error 'wrong-type-arg "time-difference: time types must match"
+               (list (time-type time1) (time-type time2))))
+      (set-time-type! time3 TIME-DURATION)
+      (if (and (= (time-second time1) (time-second time2))
+               (= (time-nanosecond time1) (time-nanosecond time2)))
+        (begin
+          (set-time-second! time3 0)
+          (set-time-nanosecond! time3 0))
+        (receive (nanos secs)
+                 (priv:nanoseconds->values (- (priv:time->nanoseconds time1)
+                                              (priv:time->nanoseconds time2)))
+          (set-time-second! time3 secs)
+          (set-time-nanosecond! time3 nanos)))
+      time3)
+
+    (define (time-difference time1 time2)
+      (priv:time-difference time1 time2 (%make-time TIME-DURATION 0 0)))
 
     ;; ====================
     ;; Current time and clock resolution
diff --git a/tests/goldfish/liii/time-test.scm b/tests/goldfish/liii/time-test.scm
index 86e5b1c9..267583ec 100644
--- a/tests/goldfish/liii/time-test.scm
+++ b/tests/goldfish/liii/time-test.scm
@@ -339,6 +339,59 @@ wrong-type-arg
   (check (time-nanosecond t3) => 0)
   (check (time-second t3) => -1234567890))
 
+#|
+time-difference
+计算两个时间对象的差值。
+
+语法
+----
+(time-difference time1 time2)
+
+参数
+----
+time1 : time?
+time2 : time?
+两个时间对象，类型必须相同。
+
+返回值
+-----
+time?
+返回一个 TIME-DURATION 类型的时间对象。
+
+错误处理
+--------
+wrong-type-arg
+当参数不是时间对象或类型不匹配时抛出错误。
+|#
+
+;; Test time-difference
+(let* ((t1 (make-time TIME-UTC 100 5))
+       (t2 (make-time TIME-UTC 900000000 3))
+       (d  (time-difference t1 t2)))
+  (check (time-type d) => TIME-DURATION)
+  (check (time-second d) => 1)
+  (check (time-nanosecond d) => 100000100))
+
+;; Test negative duration normalization
+(let* ((t1 (make-time TIME-UTC 100 5))
+       (t2 (make-time TIME-UTC 900000000 5))
+       (d  (time-difference t1 t2)))
+  (check (time-second d) => -1)
+  (check (time-nanosecond d) => 100000100))
+
+;; Test zero difference
+(let* ((t1 (make-time TIME-UTC 123456789 42))
+       (d  (time-difference t1 t1)))
+  (check (time-second d) => 0)
+  (check (time-nanosecond d) => 0))
+
+;; Test error conditions
+(check-catch 'wrong-type-arg
+  (time-difference (make-time TIME-UTC 0 0)
+                   (make-time TIME-TAI 0 0)))
+(check-catch 'wrong-type-arg
+  (time-difference "not-time" (make-time TIME-UTC 0 0)))
+
 ;; Test error conditions
 (check-catch 'wrong-type-arg (time-type "not-a-time"))
 (check-catch 'wrong-type-arg (time-nanosecond 123))

From d0022eb816b377d8d0e59d4b508d668c34edbe1c Mon Sep 17 00:00:00 2001
From: JackChen <17683835261@163.com>
Date: Wed, 11 Feb 2026 09:30:34 +0800
Subject: [PATCH 2/4] time-difference

---
 devel/210_13.md           | 16 ++++++++++++++++
 goldfish/srfi/srfi-19.scm | 21 ++++++---------------
 2 files changed, 22 insertions(+), 15 deletions(-)
 create mode 100644 devel/210_13.md

diff --git a/devel/210_13.md b/devel/210_13.md
new file mode 100644
index 00000000..18f9f4b1
--- /dev/null
+++ b/devel/210_13.md
@@ -0,0 +1,16 @@
+# [210_13] srfi-19 time-difference实现
+
+## 添加 srfi-19 time-difference实现
+
+
+## 如何测试
+
+```shell
+# 可能需要清除缓存
+# rm .xmake/ build/ -r
+xmake f -vyD
+xmake b goldfish
+./bin/goldfish tests/goldfish/liii/time-test.scm
+```
+
+
diff --git a/goldfish/srfi/srfi-19.scm b/goldfish/srfi/srfi-19.scm
index 9272b992..e0b6d676 100644
--- a/goldfish/srfi/srfi-19.scm
+++ b/goldfish/srfi/srfi-19.scm
@@ -160,27 +160,18 @@
       (+ (* (time-second time) priv:NANO)
          (time-nanosecond time)))
 
-    (define (priv:nanoseconds->values nanoseconds)
-      (receive (sec ns) (floor/ nanoseconds priv:NANO)
-        (values ns sec)))
-
     (define (priv:time-difference time1 time2 time3)
       (unless (and (time? time1) (time? time2))
         (error 'wrong-type-arg "time-difference: time1 and time2 must be time objects" (list time1 time2)))
       (unless (eq? (time-type time1) (time-type time2))
         (error 'wrong-type-arg "time-difference: time types must match"
                (list (time-type time1) (time-type time2))))
-      (set-time-type! time3 TIME-DURATION)
-      (if (and (= (time-second time1) (time-second time2))
-               (= (time-nanosecond time1) (time-nanosecond time2)))
-        (begin
-          (set-time-second! time3 0)
-          (set-time-nanosecond! time3 0))
-        (receive (nanos secs)
-                 (priv:nanoseconds->values (- (priv:time->nanoseconds time1)
-                                              (priv:time->nanoseconds time2)))
-          (set-time-second! time3 secs)
-          (set-time-nanosecond! time3 nanos)))
+      (receive (secs nanos)
+               (floor/ (- (priv:time->nanoseconds time1)
+                          (priv:time->nanoseconds time2))
+                       priv:NANO)
+        (set-time-second! time3 secs)
+        (set-time-nanosecond! time3 nanos))
       time3)
 
     (define (time-difference time1 time2)

From 5c6e82b497776c10320f90c7518aedd98286ee39 Mon Sep 17 00:00:00 2001
From: JackChen <17683835261@163.com>
Date: Wed, 11 Feb 2026 09:32:18 +0800
Subject: [PATCH 3/4] =?UTF-8?q?=E6=96=87=E6=A1=A3?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 devel/210_13.md | 1 -
 1 file changed, 1 deletion(-)

diff --git a/devel/210_13.md b/devel/210_13.md
index 18f9f4b1..1b798369 100644
--- a/devel/210_13.md
+++ b/devel/210_13.md
@@ -2,7 +2,6 @@
 
 ## 添加 srfi-19 time-difference实现
 
-
 ## 如何测试
 
 ```shell

From 84c88723e56904237119c0963d5b6f1f3e7ba76d Mon Sep 17 00:00:00 2001
From: JackChen <17683835261@163.com>
Date: Wed, 11 Feb 2026 09:43:22 +0800
Subject: [PATCH 4/4] =?UTF-8?q?=E6=97=B6=E9=97=B4=E7=B1=BB=E5=9E=8B?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 tests/goldfish/liii/time-test.scm | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tests/goldfish/liii/time-test.scm b/tests/goldfish/liii/time-test.scm
index 267583ec..b3e4ce7e 100644
--- a/tests/goldfish/liii/time-test.scm
+++ b/tests/goldfish/liii/time-test.scm
@@ -351,17 +351,17 @@ time-difference
 ----
 time1 : time?
 time2 : time?
-两个时间对象，类型必须相同。
+两个时间对象，时间类型必须相同。
 
 返回值
 -----
 time?
-返回一个 TIME-DURATION 类型的时间对象。
+返回一个 TIME-DURATION 时间类型的时间对象。
 
 错误处理
 --------
 wrong-type-arg
-当参数不是时间对象或类型不匹配时抛出错误。
+当参数不是时间对象或时间类型不匹配时抛出错误。
 |#
 
 ;; Test time-difference