м после учебника ядра отВот

У меня проблемы с компиляцией моих файлов.

я получаю следующие ошибки при попытке компиляции:

main.c:8: error: expected declaration specifiers or ‘...’ before ‘size_t’
main.c:8: error: conflicting types for ‘memcpy’                          
./include/system.h:5: note: previous declaration of ‘memcpy’ was here    
main.c: In function ‘memcpy’:                                            
main.c:12: error: ‘count’ undeclared (first use in this function)        
main.c:12: error: (Each undeclared identifier is reported only once      
main.c:12: error: for each function it appears in.)                      
main.c: At top level:                                                    
main.c:16: error: expected declaration specifiers or ‘...’ before ‘size_t’
main.c:16: error: conflicting types for ‘memset’
./include/system.h:6: note: previous declaration of ‘memset’ was here
main.c: In function ‘memset’:
main.c:19: error: ‘count’ undeclared (first use in this function)
main.c: At top level:
main.c:23: error: expected declaration specifiers or ‘...’ before ‘size_t’
main.c:23: error: conflicting types for ‘memsetw’
./include/system.h:7: note: previous declaration of ‘memsetw’ was here
main.c: In function ‘memsetw’:
main.c:26: error: ‘count’ undeclared (first use in this function)
main.c: At top level:
main.c:30: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘strlen’
main.c:49: warning: return type of ‘main’ is not ‘int’
main.c: In function ‘main’:
main.c:64: warning: pointer targets in passing argument 1 of ‘puts’ differ in    signedness
./include/system.h:13: note: expected ‘unsigned char *’ but argument is of type ‘char *’
main.c:51: warning: unused variable ‘i’
scrn.c: In function ‘scroll’:
scrn.c:24: warning: passing argument 1 of ‘memcpy’ from incompatible pointer type
./include/system.h:5: note: expected ‘unsigned char *’ but argument is of type ‘short unsigned int *’
scrn.c:24: warning: passing argument 2 of ‘memcpy’ from incompatible pointer type
./include/system.h:5: note: expected ‘const unsigned char *’ but argument is of type  ‘short unsigned int *’
scrn.c: In function ‘puts’:
scrn.c:139: warning: pointer targets in passing argument 1 of ‘strlen’ differ in signedness
./include/system.h:8: note: expected ‘const char *’ but argument is of type ‘unsigned char *’

Мои файлы являются точными копиями из учебника.

Я вижу, что в main.c функции определены так

void *memcpy(void *dest,const void *src, size_t count)

но в моем файле system.h они определены так

extern unsigned char *memcpy(unsigned char *dest,const unsigned char *src, int count)

C не мой основной язык, но я нахожусь в процессе его изучения, поэтому я прошу прощения, если мой вопрос прост, но я думаю, что эти определения не должны быть одинаковыми?