remove the c_

Author: stewpend0us

.gitignore

@@ -1,4 +1,4 @@
-c_iir_test
+iir_test
 *~
 *.o
 *.swp

Makefile

@@ -2,13 +2,13 @@ CFLAGS+=-Wall -Wextra -Wpedantic
 LDFLAGS+=-DFLOAT_TYPE=double
 
 .PHONY: all test clean
-all: c_iir_test
+all: iir_test
 
-c_iir_test: c_iir_test.c c_iir.c
+iir_test: iir_test.c iir.c
 	cc $(CFLAGS) -o $@ $^ $(LDFLAGS)
 
-test: c_iir_test
-	./c_iir_test
+test: iir_test
+	./iir_test
 
 clean:
-	rm -rf *.o *~ c_iir_test
+	rm -rf *.o *~ iir_test

c_iir.c iir.c

@@ -22,11 +22,11 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 */
 
-#include "c_iir.h"
+#include "iir.h"
 #include <string.h>
 #include <stdio.h>
 
-FLOAT_TYPE iir_calculate( const struct c_iir * iir, FLOAT_TYPE input)
+FLOAT_TYPE iir_calculate( const struct iir * iir, FLOAT_TYPE input)
 {
 	unsigned int i;
 	unsigned int num_size = iir->num_size;
@@ -49,34 +49,44 @@ FLOAT_TYPE iir_calculate( const struct c_iir * iir, FLOAT_TYPE input)
 	return result;
 }
 
-void iir_to_general_form( struct c_iir * iir )
+int iir_check( struct iir * iir )
+{
+	unsigned int num_size = iir->num_size;
+	unsigned int den_size = iir->den_size;
+	if ( num_size == 0 ) return -1; //cannot have a zero size numerator
+	if ( den_size < num_size ) return -2; //requirement of 'standard programming'
+	return 0;
+	
+}
+
+void iir_to_general_form( struct iir * iir )
 {
 	unsigned int num_size = iir->num_size;
 	unsigned int den_size = iir->den_size;
 	FLOAT_TYPE * num = iir->num;
 	FLOAT_TYPE * den = iir->den;
-	FLOAT_TYPE val = den[0];
+	FLOAT_TYPE first = den[0];
 
-	if (val != 1.0)
+	if (first != 1.0)
 	{
 		unsigned int i;
 		for (i = 0; i < num_size; i++)
 		{
-			num[i] /= val;
+			num[i] /= first;
 		}
 		for (i = 0; i < den_size; i++)
 		{
-			den[i] /= val;
+			den[i] /= first;
 		}
 	}
 }
 
-void iir_init_zero( struct c_iir * iir )
+void iir_init_zero( struct iir * iir )
 {
 	memset( iir->history, 0, sizeof(FLOAT_TYPE) * iir->den_size);				\
 }
 
-FLOAT_TYPE iir_dc_gain( const struct c_iir * iir )
+FLOAT_TYPE iir_dc_gain( const struct iir * iir )
 {
 	unsigned int i;
 	unsigned int num_size = iir->num_size;

c_iir.h iir.h

@@ -22,22 +22,34 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 */
 
-#ifndef _C_IIR_H_
-#define _C_IIR_H_
+/*
+Implement the "Standard Programming" approach as described
+in "Discrete-Time Control Systems" by Katsuhiko Ogata for
+the general form of the transfer function:
+	Output(z)    b[0] + b[1]*z^-1 + b[2]*z^-2 + ... + b[m]*z^-m
+	--------- = ------------------------------------------------
+	Input(z)     a[0] + a[1]*z^-1 + a[2]*z^-2 + ... + a[n]*z^-n
+
+The "Standard Programming" approach requires:
+	n >= m
+	a[0] == 1
+	size(history) == n
+*/
+
+#ifndef _IIR_H_
+#define _IIR_H_
 
 #ifndef FLOAT_TYPE
 #error FLOAT_TYPE must be specified
 #endif
 
-//#include <assert.h>
-
 #define IIR_SIZE(arr) (sizeof(arr)/sizeof(arr[0]))
 #define IIR_ARRAY(...) {__VA_ARGS__}
 #define IIR_INIT(name, num, den)							\
 FLOAT_TYPE name##_num[] = num;								\
 FLOAT_TYPE name##_den[] = den;								\
 FLOAT_TYPE name##_history[] = den;							\
-struct c_iir name =									\
+struct iir name =									\
 {											\
 	IIR_SIZE(name##_num),								\
 	IIR_SIZE(name##_den),								\
@@ -46,22 +58,8 @@ struct c_iir name =									\
 	name##_history									\
 };											\
 iir_init_zero( &name )
-//assert( name.num_size > 0 && "cannot have a zero size numerator" );
-//assert( name.den_size > 0 && "cannot have a zero size denominator" );
-//assert( name.den_size >= name.num_size && "requirement of 'standard programming'" )
-
-/*
-struct c_iir represents a general discrete time transfer function such as:
 
-	Output(z)    b[0] + b[1]*z^-1 + b[2]*z^-2 + ... + b[m]*z^-m
-	--------- = ------------------------------------------------
-	Input(z)     a[0] + a[1]*z^-1 + a[2]*z^-2 + ... + a[n]*z^-n
-
-Where:
-	b is an array of length m that represents the numerator coefficients.
-	a is an array of length n that represents the denominator coefficients.
-*/
-struct c_iir
+struct iir
 {
 	unsigned int num_size; // number of elements in num
 	unsigned int den_size; // number of elements in den
@@ -70,26 +68,19 @@ struct c_iir
 	FLOAT_TYPE * history; // pointer to array of size den_size
 };
 
-/*
-IIR_calculate implements the "Standard Programming" approach as described
-in "Discrete-Time Control Systems" by Katsuhiko Ogata.
+//calculate the transfer function output for the current step
+FLOAT_TYPE iir_calculate( const struct iir * iir, FLOAT_TYPE input );
 
-The "Standard Programming" approach requires:
-n >= m
-a[0] == 1
-size(history) == n
-*/
-FLOAT_TYPE iir_calculate( const struct c_iir * iir, FLOAT_TYPE input );
+//return 0 if some basic requirements are met
+int iir_check( struct iir * iir );
 
-/*
-check if iir is in the general form and updates it if possible.
-*/
-void iir_to_general_form( struct c_iir * iir );
+//check if iir is in the general form and updates it if possible.
+void iir_to_general_form( struct iir * iir );
 
-/**/
-void iir_init_zero( struct c_iir * iir );
+//zero out the history
+void iir_init_zero( struct iir * iir );
 
-/**/
-FLOAT_TYPE iir_dc_gain( const struct c_iir * iir );
+//compute the "dc gain" of the transfer function
+FLOAT_TYPE iir_dc_gain( const struct iir * iir );
 
 #endif

c_iir_test.c iir_test.c

@@ -22,7 +22,7 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 */
 
-#include "c_iir.h"
+#include "iir.h"
 #include <stdio.h>
 
 #define EPS 1.0E-14
@@ -31,7 +31,7 @@ SOFTWARE.
 #define BACK(i) "\x1B[48;5;" #i "m"
 #define RESET "\x1b[0m"
 
-void run_test( FLOAT_TYPE * input, int in_count, FLOAT_TYPE * expected, int expected_count, const struct c_iir * iir, const char name[] )
+void run_test( FLOAT_TYPE * input, int in_count, FLOAT_TYPE * expected, int expected_count, const struct iir * iir, const char name[] )
 {
 	printf("TEST %s:\n", name );
 	FLOAT_TYPE output, error;