fix BPM rounding error (monome#302)

scanner-darkly · Feb 2, 2023 · abf9784 · abf9784
1 parent 9f8c9e9
commit abf9784
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Showing 3 changed files with 4 additions and 1 deletion.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -16,6 +16,7 @@
 - **FIX**: reset M timer when changing metro rate
 - **NEW**: new Drum Ops: `DR.T`, `DR.V`, `DR.P`
 - **NEW**: [I2C2MIDI](https://github.com/attowatt/i2c2midi) ops
+- **FIX**: fix BPM rounding error
 
 ## v4.0.0
 

diff --git a/docs/whats_new.md b/docs/whats_new.md
@@ -16,6 +16,7 @@
 - **FIX**: reset M timer when changing metro rate
 - **NEW**: drum ops: `DR.P`, `DR.V`, `DR.TR`
 - **NEW**: [I2C2MIDI](https://github.com/attowatt/i2c2midi) ops
+- **FIX**: fix BPM rounding error
 
 ## v4.0.0
 

diff --git a/src/ops/maths.c b/src/ops/maths.c
@@ -1255,7 +1255,8 @@ static void op_BPM_get(const void *NOTUSED(data), scene_state_t *NOTUSED(ss),
     uint32_t ret;
     if (a < 2) a = 2;
     if (a > 1000) a = 1000;
-    ret = ((((uint32_t)(1 << 31)) / ((a << 20) / 60)) * 1000) >> 11;
+    ret = ((((uint32_t)(1 << 31)) / ((a << 20) / 60)) * 1000) >> 10;
+    ret = ret / 2 + (ret & 1); // rounding
     cs_push(cs, (int16_t)ret);
 }