Move some parts of the driver code into its own function.

diff --git a/driver.c b/driver.c
index dfa61ddde0ab2b70e56b8fc924ddd96012db01c7..c4f48ac6f9557df89fea22169f995bbb52c7994a 100644 (file)
--- a/driver.c
+++ b/driver.c
@@ -5,24 +5,11 @@
 #include "bytesource.h"
 #include "choice.h"
 #include "dehuff.h"
+#include "driver.h"
 #include "idct.h"
 #include "input.h"
 #include "zigzag.h"
 
-struct jpeg_image {
-       unsigned precision;
-       unsigned width, height;
-       unsigned num_components;
-       unsigned hsample[256], vsample[256], qtable[256];
-       unsigned max_hsample, max_vsample;
-       unsigned stride[256];
-       unsigned num_blocks_horizontal, num_blocks_vertical;
-       uint32_t qvalues[256][DCTSIZE2];
-       void* idct_data[256];
-       uint8_t* pixel_data[256];
-       uint8_t* pixel_write_pointer[256];
-};
-
 ssize_t stdio_read(void* userdata, uint8_t* buf, size_t count) 
 {
        return fread(buf, 1, count, (FILE*)userdata);
@@ -261,14 +248,12 @@ void skip_segment(struct byte_source* source)
        }
 }
        
-int main(void)
+void read_jpeg(struct jpeg_image* jpeg, FILE *input)
 {
-       struct jpeg_image jpeg;
-       memset(&jpeg, 0, sizeof(jpeg));
-       init_choices();
-
+       memset(jpeg, 0, sizeof(*jpeg));
+       
        struct byte_source source;
-       init_byte_source(&source, stdio_read, stdin);
+       init_byte_source(&source, stdio_read, input);
 
        huffman_tables_t tables;
 
@@ -306,11 +291,11 @@ int main(void)
                        break;
                case 0xdb:
                        /* DQT */
-                       read_dqt(&source, &jpeg);
+                       read_dqt(&source, jpeg);
                        break;
                case 0xc0:
                        /* SOF0 (baseline DCT, Huffman encoded) */
-                       read_sof(&source, &jpeg);
+                       read_sof(&source, jpeg);
                        break;
                case 0xd8:
                        /* SOI */
@@ -324,7 +309,7 @@ int main(void)
                        break;
                case 0xda:
                        /* SOS (start of scan) */
-                       read_scan(&source, &jpeg, &tables);
+                       read_scan(&source, jpeg, &tables);
                        break;
                default:
                        fprintf(stderr, "Error: Unknown marker 0x%02x\n", m2);
@@ -332,3 +317,11 @@ int main(void)
                }
        }
 }
+       
+int main(void)
+{
+       init_choices();
+
+       struct jpeg_image jpeg;
+       read_jpeg(&jpeg, stdin);
+}

diff --git a/driver.h b/driver.h
new file mode 100644 (file)
index 0000000..2a359d5
--- /dev/null
+++ b/driver.h
@@ -0,0 +1,23 @@
+#ifndef _DRIVER_H
+#define _DRIVER_H 1
+
+#include <stddef.h>
+#include "idct.h"
+
+struct jpeg_image {
+       unsigned precision;
+       unsigned width, height;
+       unsigned num_components;
+       unsigned hsample[256], vsample[256], qtable[256];
+       unsigned max_hsample, max_vsample;
+       unsigned stride[256];
+       unsigned num_blocks_horizontal, num_blocks_vertical;
+       uint32_t qvalues[256][DCTSIZE2];
+       void* idct_data[256];
+       uint8_t* pixel_data[256];
+       uint8_t* pixel_write_pointer[256];
+};
+
+void read_jpeg(struct jpeg_image* jpeg, FILE *input);
+
+#endif /* !defined(_DRIVER_H) */