eliminate SPI3w heap allocation in status read

soypat · soypat · commit 0da43683898b · 2023-12-10T17:00:48.000-03:00
diff --git a/rp2-pio/piolib/spi3w.go b/rp2-pio/piolib/spi3w.go
@@ -203,12 +203,11 @@ func (spi *SPI3w) getStatus(dl deadline) error {
 		}
 		gosched()
 	}
-	var buf [1]uint32
-	err := spi.read(buf[:1], dl)
+
+	err := spi.read(unsafe.Slice(&spi.lastStatus, 1), dl)
 	if err != nil {
 		return err
 	}
-	spi.lastStatus = buf[0]
 	return nil
 }
 

Original file line number	Diff line number	Diff line change
`@@ -203,12 +203,11 @@ func (spi *SPI3w) getStatus(dl deadline) error {`
`203`	`203`	`}`
`204`	`204`	`gosched()`
`205`	`205`	`}`
`206`		`- var buf [1]uint32`
`207`		`- err := spi.read(buf[:1], dl)`
	`206`	`+`
	`207`	`+ err := spi.read(unsafe.Slice(&spi.lastStatus, 1), dl)`
`208`	`208`	`if err != nil {`
`209`	`209`	`return err`
`210`	`210`	`}`
`211`		`- spi.lastStatus = buf[0]`
`212`	`211`	`return nil`
`213`	`212`	`}`
`214`	`213`