Fixed ioctl code and added coeff setting example code

[aic34-eq] / setcoeffs.c

diff --git a/setcoeffs.c b/setcoeffs.c
new file mode 100644 (file)
index 0000000..1ea5b10
--- /dev/null
+++ b/setcoeffs.c
@@ -0,0 +1,34 @@
+#include <stdint.h>
+#include <fcntl.h>
+#include <alsa/asoundlib.h>
+#include <alsa/hwdep.h>
+#include <stdio.h>
+
+struct iir_coeffs {
+    int16_t N0, N1, N2, D1, D2;
+    int16_t N3, N4, N5, D4, D5;
+};
+
+int main(){
+    struct iir_coeffs coeffs = {
+        .N0 = 32767, .N1 = 4265, .N2 = -10472, .D1 = -6269, .D2 = 0,
+        .N3 = 32027, .N4 = -31187, .N5 = 30352, .D4 = 31187, .D5 = -29613
+    };
+
+    snd_hwdep_t *hwdep;
+    int ret; int arg;
+    
+    ret = snd_hwdep_open(&hwdep, "hw:0,0", SND_HWDEP_OPEN_DUPLEX);
+    printf("open: %i\n", ret);
+    if(ret) return 1;
+    
+    ret = snd_hwdep_write(hwdep, (void*)&coeffs, sizeof(coeffs));
+    printf("write: %i\n", ret);
+
+    /* Set state to 2, which is 'Custom'. This writes coeffs to hardware
+     * and enables filter */
+    arg = 2;
+    ret = snd_hwdep_ioctl(hwdep, 1, &arg);
+    printf("ioctl: %i\n", ret);
+    return 0;
+}