From 3f2af32442b9384d316651d42ad35945533dc39e Mon Sep 17 00:00:00 2001
From: Federico Angelilli <code@fedang.net>
Date: Mon, 11 Nov 2024 23:26:33 +0100
Subject: Add timespec utils

---
 src/block.c |  2 +-
 src/comet.c |  2 +-
 src/util.c  | 47 ++++++++++++++++++++++++++++++++++++++++++-----
 src/util.h  | 17 ++++++++++++++++-
 4 files changed, 60 insertions(+), 8 deletions(-)

diff --git a/src/block.c b/src/block.c
index d0b66c9..29a8394 100644
--- a/src/block.c
+++ b/src/block.c
@@ -9,7 +9,7 @@ void block_update(block_t *block)
     if (block->update_cb != NULL) {
         struct timespec now, diff;
         timespec_get(&now, TIME_UTC);
-        diff = timespec_diff(block->update_last, now);
+        diff = timespec_diff(now, block->update_last);
 
         if (timespec_greater(diff, block->update_interval)) {
             log_value_trace("Updating block",
diff --git a/src/comet.c b/src/comet.c
index 6fccb3d..a539015 100644
--- a/src/comet.c
+++ b/src/comet.c
@@ -124,7 +124,7 @@ int main(int argc, char **argv)
         layout_free(&layout);
 
         timespec_get(&end, TIME_UTC);
-        diff = timespec_diff(timespec_diff(end, start), rate);
+        diff = timespec_diff(rate, timespec_diff(end, start));
         nanosleep(&diff, NULL);
     }
 
diff --git a/src/util.c b/src/util.c
index 805d397..669e031 100644
--- a/src/util.c
+++ b/src/util.c
@@ -28,14 +28,46 @@ void color_print(FILE *stream, color_t *color)
     fprintf(stream, "#%02x%02x%02x%02x", r, g, b, a);
 }
 
+const struct timespec timespec_from_ms(long ms)
+{
+    struct timespec ts = {
+        .tv_sec = ms / 1000,
+        .tv_nsec = (ms % 1000) * 1000000ul,
+    };
+    return ts;
+}
+
+const long timespec_to_ms(struct timespec ts)
+{
+    return (ts.tv_sec * 1000) + (ts.tv_nsec / 1000000ul);
+}
+
 struct timespec timespec_diff(struct timespec a, struct timespec b)
 {
-    bool over = (b.tv_nsec - a.tv_nsec) < 0;
-    struct timespec diff = {
-        .tv_sec = b.tv_sec - a.tv_sec - over,
-        .tv_nsec = b.tv_nsec - a.tv_nsec + over * 1000000000ul,
+    bool over = (a.tv_nsec - b.tv_nsec) < 0;
+    struct timespec ts = {
+        .tv_sec = a.tv_sec - b.tv_sec - over,
+        .tv_nsec = a.tv_nsec - b.tv_nsec + over * 1000000000ul,
     };
-    return diff;
+    return ts;
+}
+
+struct timespec timespec_add(struct timespec a, struct timespec b)
+{
+    bool over = (a.tv_nsec + b.tv_nsec) > 1000000000ul;
+    struct timespec ts = {
+        .tv_sec = a.tv_sec + b.tv_sec + over,
+        .tv_nsec = a.tv_nsec + b.tv_nsec - over * 1000000000ul,
+    };
+    return ts;
+}
+
+struct timespec timespec_div(struct timespec ts, int n)
+{
+    ts.tv_nsec /= n;
+    ts.tv_nsec += ((ts.tv_sec % n) * 1000000000ul) / n;
+    ts.tv_sec /= n;
+    return ts;
 }
 
 bool timespec_greater(struct timespec a, struct timespec b)
@@ -44,6 +76,11 @@ bool timespec_greater(struct timespec a, struct timespec b)
         || (a.tv_sec == b.tv_sec && a.tv_nsec > b.tv_nsec);
 }
 
+bool timespec_zero(struct timespec ts)
+{
+    return ts.tv_sec == 0 && ts.tv_nsec == 0;
+}
+
 void timespec_print(FILE *stream, struct timespec *ts)
 {
     fprintf(stream, "%ld.%.9ld", ts->tv_sec, ts->tv_nsec);
diff --git a/src/util.h b/src/util.h
index 770790d..d7eafb5 100644
--- a/src/util.h
+++ b/src/util.h
@@ -6,7 +6,7 @@
 #include <stdbool.h>
 #include <stdio.h>
 
-#define unreachable() log_panic("Unreachable code");
+#define unreachable() log_panic("The impossible happened");
 
 // Color representation normalized to [0, 1]
 //
@@ -25,14 +25,29 @@ static inline color_t color_rgb(int r, int g, int b)
     return color_rgba(r, g, b, 255);
 }
 
+static inline color_t color_hex(unsigned int h)
+{
+    return color_rgb((h >> 16) & 0xff, (h >>  8) & 0xff, h & 0xff);
+}
+
 char *color_to_string(color_t *color);
 
 void color_print(FILE *stream, color_t *color);
 
+const struct timespec timespec_from_ms(long ms);
+
+const long timespec_to_ms(struct timespec ts);
+
 struct timespec timespec_diff(struct timespec a, struct timespec b);
 
+struct timespec timespec_add(struct timespec a, struct timespec b);
+
+struct timespec timespec_div(struct timespec ts, int n);
+
 bool timespec_greater(struct timespec a, struct timespec b);
 
+bool timespec_zero(struct timespec ts);
+
 void timespec_print(FILE *stream, struct timespec *ts);
 
 // Check if point (px, py) is inside a rectangle in (x, y), (x+w, y), (x, y+h) and (w+h, y+h)
-- 
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