1 files changed, 89 insertions, 0 deletions
diff --git a/lib/cci.c b/lib/cci.c
new file mode 100644
index 0000000..956f619
--- /dev/null
+++ b/lib/cci.c
@@ -0,0 +1,89 @@
+// Commodity Channel Index
+//
+// cci - CCI
+//
+// (TP - SMA(TP)) / (0.015 * MAD(TP)), where TP = (H+L+C)/3
+//
+// Inputs:    4 (OHLC)
+// Outputs:   1 (CCI)
+// Constants: 0
+
+#include <math.h>
+#include "ts.h"
+
+typedef struct {
+    uint_t k;
+} ts_cci_params_t;
+
+ts_parameter_t const ts_cci_p = { .n_inputs = 4, .n_outputs = 1, .n_constants = 1, .params_size = sizeof(ts_cci_params_t) };
+
+uint_t ts_cci_offset( ts_constant_t const *c )
+{
+	( void )c;
+	return ( c ? ((ts_cci_params_t *)c)->k - 1 : 0 );
+}
+
+int ts_cci(
+	fp_t * const *y, uint_t y_n,
+	fp_t const * const *x, uint_t x_n,
+	uint_t n, ts_constant_t const *c
+)
+{
+	TS_PROLOGUE( ts_cci_p );
+	if ( !c ) return -1;
+	TS_CHECK_INPUT(x, x_n, n);
+	uint_t k = ((ts_cci_params_t *)c)->k;
+	if (k == 0 || n < k) return -1;
+
+	// Compute initial typical prices
+	fp_t tp_sum = 0;
+	for( uint_t j = 0; j < k; ++j )
+	{
+		tp_sum += ( ts_h( x, j ) + ts_l( x, j ) + ts_c( x, j ) ) / 3.0;
+	}
+	fp_t tp_sma = tp_sum / (fp_t)k;
+
+	// Compute initial MAD
+	fp_t mad_sum = 0;
+	for( uint_t j = 0; j < k; ++j )
+	{
+		fp_t tp = ( ts_h( x, j ) + ts_l( x, j ) + ts_c( x, j ) ) / 3.0;
+		mad_sum += fabs( tp - tp_sma );
+	}
+	fp_t mad = mad_sum / (fp_t)k;
+
+	{
+		fp_t tp = ( ts_h( x, k - 1 ) + ts_l( x, k - 1 ) + ts_c( x, k - 1 ) ) / 3.0;
+		if( mad == 0 )
+			y[0][k - 1] = 0;
+		else
+			y[0][k - 1] = ( tp - tp_sma ) / ( 0.015 * mad );
+	}
+
+	// Sliding window: incremental tp_sum, but MAD needs recompute when tp_sma changes
+	// MAD depends on tp_sma which changes each step, so we can't fully incremental MAD
+	// However, we can still use incremental tp_sum
+	for( uint_t i = k; i < n; ++i )
+	{
+		fp_t tp_new = ( ts_h( x, i ) + ts_l( x, i ) + ts_c( x, i ) ) / 3.0;
+		fp_t tp_old = ( ts_h( x, i - k ) + ts_l( x, i - k ) + ts_c( x, i - k ) ) / 3.0;
+		tp_sum = tp_sum + tp_new - tp_old;
+		tp_sma = tp_sum / (fp_t)k;
+
+		mad_sum = 0;
+		for( uint_t j = 0; j < k; ++j )
+		{
+			fp_t tp = ( ts_h( x, i - k + 1 + j ) + ts_l( x, i - k + 1 + j ) + ts_c( x, i - k + 1 + j ) ) / 3.0;
+			mad_sum += fabs( tp - tp_sma );
+		}
+		mad = mad_sum / (fp_t)k;
+
+		if( mad == 0 )
+			y[0][i] = 0;
+		else
+			y[0][i] = ( tp_new - tp_sma ) / ( 0.015 * mad );
+	}
+
+	return 0;
+}
+