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path: root/kernel/usrbin/print.c
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2018-06-24Re-structured the source tree and modified makefiles accordingly.Jake Mannens
Hopefully further separation will help to keep the code readable and understandable.
2018-06-24Modified makefiles to use the more appropriate variable $(MAKE) whenJake Mannens
invoking the tool recursively. Disabled GCC's position-independent-code generation in makefiles. Modified makefile for kernel/usrbin so that it now compiles and links C code into the userspace test. Created errno.h and populated it with standard error definitions. Replaced the va_list based system call handlers with a system call table defined in the header kernel/sys.h. NOTE: This header is included in kmain.c and should ONLY be included there! Do NOT include this header in sys.c. Rather than fetching the user's stack pointer and using it to initialize a va_list, parameters are now passed to the call handlers via the general purpose registers EAX, EBX, ECX and EDX where EAX contains the requested call number and conveys the return value. Setup macros in unistd.h to aid to making system calls from userspace. Implemented two basic system calls; sys_print and sys_dummy. The former takes a single char* argument and displays it on screen whilst the latter is used to populate otherwise empty entries of the system call table. sys_dummy returns the error ENOSYS whenever it is called.