From a3ad1e62d95d54e882c78f7aa9fbdeaea8f582f1 Mon Sep 17 00:00:00 2001
From: Michael Ossmann <mike@ossmann.com>
Date: Sun, 22 Nov 2015 12:53:10 -0700
Subject: [PATCH] converters for signed chars, compatible with hackrf_transfer

---
 README.md |  2 ++
 csdr.c    | 25 +++++++++++++++++++++++++
 libcsdr.c | 10 ++++++++++
 libcsdr.h |  2 ++
 4 files changed, 39 insertions(+)

diff --git a/README.md b/README.md
index 1742454..138bf38 100644
--- a/README.md
+++ b/README.md
@@ -122,6 +122,8 @@ The following commands are available:
 
 - `csdr convert_u8_f` 
 - `csdr convert_f_u8` 
+- `csdr convert_s8_f`
+- `csdr convert_f_s8`
 - `csdr convert_i16_f` 
 - `csdr convert_f_i16`
 
diff --git a/csdr.c b/csdr.c
index 0b64829..56b9deb 100644
--- a/csdr.c
+++ b/csdr.c
@@ -55,6 +55,8 @@ char usage[]=
 "list of functions:\n\n"
 "    convert_u8_f\n"
 "    convert_f_u8\n"
+"    convert_s8_f\n"
+"    convert_f_s8\n"
 "    convert_f_i16\n"
 "    convert_i16_f\n"
 "    realpart_cf\n"
@@ -204,6 +206,7 @@ int main(int argc, char *argv[])
 {	
 	static float input_buffer[BIG_BUFSIZE*2];
 	static unsigned char buffer_u8[BIG_BUFSIZE*2];
+	static signed char buffer_s8[BIG_BUFSIZE*2];
 	static float output_buffer[BIG_BUFSIZE*2];
 	static short buffer_i16[BIG_BUFSIZE*2];
 	static float temp_f[BIG_BUFSIZE*4];
@@ -231,6 +234,28 @@ int main(int argc, char *argv[])
 			TRY_YIELD;
 		}
 	}
+	if(!strcmp(argv[1],"convert_s8_f"))
+	{
+		for(;;)
+		{
+			FEOF_CHECK;
+			fread(buffer_s8, sizeof(signed char), BUFSIZE, stdin);
+			convert_s8_f(buffer_s8, output_buffer, BUFSIZE);
+			FWRITE_R;
+			TRY_YIELD;
+		}
+	}
+	if(!strcmp(argv[1],"convert_f_s8")) //not tested
+	{
+		for(;;)
+		{
+			FEOF_CHECK;
+			FREAD_R;
+			convert_f_s8(input_buffer, buffer_s8, BUFSIZE);
+			fwrite(buffer_s8, sizeof(signed char), BUFSIZE, stdout);
+			TRY_YIELD;
+		}
+	}
 	if(!strcmp(argv[1],"convert_f_i16"))
 	{
 		for(;;)
diff --git a/libcsdr.c b/libcsdr.c
index 2cf5e9b..a767727 100644
--- a/libcsdr.c
+++ b/libcsdr.c
@@ -805,6 +805,11 @@ void convert_u8_f(unsigned char* input, float* output, int input_size)
 	for(int i=0;i<input_size;i++) output[i]=((float)input[i])/(UCHAR_MAX/2.0)-1.0; //@convert_u8_f
 }
 
+void convert_s8_f(signed char* input, float* output, int input_size)
+{
+	for(int i=0;i<input_size;i++) output[i]=((float)input[i])/SCHAR_MAX; //@convert_s8_f
+}
+
 void convert_i16_f(short* input, float* output, int input_size)
 {
 	for(int i=0;i<input_size;i++) output[i]=(float)input[i]/SHRT_MAX; //@convert_i16_f
@@ -817,6 +822,11 @@ void convert_f_u8(float* input, unsigned char* output, int input_size)
 	//of at least -60 dB is shown on the FFT plot after convert_f_u8 -> convert_u8_f
 }
 
+void convert_f_s8(float* input, signed char* output, int input_size)
+{
+	for(int i=0;i<input_size;i++) output[i]=input[i]*SCHAR_MAX; //@convert_f_s8
+}
+
 void convert_f_i16(float* input, short* output, int input_size)
 {
 	/*for(int i=0;i<input_size;i++) 
diff --git a/libcsdr.h b/libcsdr.h
index 9977402..48ff5b5 100644
--- a/libcsdr.h
+++ b/libcsdr.h
@@ -164,6 +164,8 @@ void gain_ff(float* input, float* output, int input_size, float gain);
 
 void convert_u8_f(unsigned char* input, float* output, int input_size);
 void convert_f_u8(float* input, unsigned char* output, int input_size);
+void convert_s8_f(signed char* input, float* output, int input_size);
+void convert_f_s8(float* input, signed char* output, int input_size);
 void convert_f_i16(float* input, short* output, int input_size);
 void convert_i16_f(short* input, float* output, int input_size);