jabyengine/include/PSX/System/syscalls.hpp

#pragma once
#include "../jabyengine_defines.h"

/*
R0	    zr	    Constant Zero	
R1	    at	    Reserved for the assembler	
R2-R3	v0-v1	Values for results and expression evaluation	
R4-R7	a0-a3	Arguments	
R8-R15	t0-t7	Temporaries (not preserved across call)	
R16-R23	s0-s7	Saved (preserved across call)	
R24-R25	t8-t9	More temporaries (not preserved across call)	
R26-R27	k0-k1	Reserved for OS Kernel	
R28	    gp	    Global Pointer	
R29	    sp	    Stack Pointer	
R30	    fp	    Frame Pointer	
R31 	ra	    Return address (set by function call)
*/

namespace JabyEngine {
    namespace SysCall {
        static constexpr const uint32_t Table_A = 0xA0;
        static constexpr const uint32_t Table_B = 0xB0;
        static constexpr const uint32_t Table_C = 0xC0;

        enum struct Priority {
            CdromDmaIrq      = 0, 
            CdromIoIrq       = 0, 
            SyscallException = 0,

            CardSpecificIrq = 1,
            VblankIrq       = 1,
            Timer2Irq       = 1,
            Timer1Irq       = 1,
            Timer0Irq       = 1,

            PadCardIrq = 2,

            DefInt = 3
        };

        enum InterruptVerifierResult {
            SkipHandler    = 0,
            ExecuteHandler = 1
        };

        typedef InterruptVerifierResult (*InterruptVerifier)();
        typedef uint32_t (*InterruptHandler)(uint32_t);

        #pragma pack(push, 1)
        struct InterrupCallback {
            struct InterrupCallback* next;
            InterruptHandler         handler_function;
            InterruptVerifier        verifier_function;
            uint32_t                 notUsed;
        };
        #pragma pack(pop)

        #define __syscall_function_cast(table, ...) reinterpret_cast<__VA_ARGS__>(table)

        static __always_inline void* memcpy(void *dst, const void *src, size_t len) {
            register uint32_t FuncID asm("t1") = 0x2A;
            __asm__ volatile("" : "=r"(FuncID) : "r"(FuncID));

            return __syscall_function_cast(Table_A, void*(*)(void*, const void*, size_t))(dst, src, len);
        }

        static __always_inline void InitPad(uint8_t *portA, uint32_t portASize, uint8_t *portB, uint32_t portBSize) {
            register uint32_t FuncID asm("t1") = 0x12;
            __asm__ volatile("" : "=r"(FuncID) : "r"(FuncID));

            __syscall_function_cast(Table_B, void(*)(uint8_t*, uint32_t, uint8_t*, uint32_t))(portA, portASize, portB, portBSize);
        }

        static __always_inline void StartPad() {
            register uint32_t FuncID asm("t1") = 0x13;
            __asm__ volatile("" : "=r"(FuncID) : "r"(FuncID));

            __syscall_function_cast(Table_B, void(*)())();
        }

        static __always_inline void StopPad() {
            register uint32_t FuncID asm("t1") = 0x14;
            __asm__ volatile("" : "=r"(FuncID) : "r"(FuncID));

            __syscall_function_cast(Table_B, void(*)())();
        }

        static __always_inline void ChangeClearPad(int32_t _reserved) {
            register uint32_t FuncID asm("t1") = 0x5B;
            __asm__ volatile("" : "=r"(FuncID) : "r"(FuncID));

            __syscall_function_cast(Table_B, void(*)(int32_t))(_reserved);
        }

        static __always_inline void [[noreturn]] ReturnFromException() {
            register uint32_t FuncID asm("t1") = 0x17;
            __asm__ volatile("" : "=r"(FuncID) : "r"(FuncID));

            __syscall_function_cast(Table_B, void(*)())();
        }

        static __always_inline int SysEnqIntRP(Priority prio, InterrupCallback* interElm) {
            register uint32_t FuncID asm("t1") = 0x02;
            __asm__ volatile("" : "=r"(FuncID) : "r"(FuncID));

            return __syscall_function_cast(Table_C, int(*)(Priority prio, InterrupCallback *interElm))(prio, interElm);
        }

        static __always_inline int SysDeqIntRP(Priority prio, InterrupCallback *interElm) {
            register uint32_t FuncID asm("t1") = 0x03;
            __asm__ volatile("" : "=r"(FuncID) : "r"(FuncID));

            return __syscall_function_cast(Table_C, int(*)(Priority prio, InterrupCallback *interElm))(prio, interElm);
        }

        static __always_inline uint32_t EnterCriticalSection() {
            register uint32_t FuncID      asm("a0") = 0x01;
            register uint32_t returnValue asm("v0");

            __asm__ volatile("syscall" : "=r"(FuncID), "=r"(returnValue) : "r"(FuncID) : "at", "v1", "a1", "a2", "a3", "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9", "memory");
            return returnValue;
        }

        static __always_inline void ExitCriticalSection() {
            register uint32_t FuncID asm("a0") = 0x02;

            __asm__ volatile("syscall" : "=r"(FuncID) : "r"(FuncID) : "at", "v0", "v1", "a1", "a2", "a3", "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9", "memory");
        }

        static __always_inline void DeliverEvent(uint32_t classId, uint32_t spec) {
            register uint32_t FuncID asm("t1") = 0x07;
            
            __asm__ volatile("" : "=r"(FuncID) : "r"(FuncID));
            __syscall_function_cast(Table_B, void (*)(uint32_t, uint32_t))(classId, spec);
        }

        static __always_inline uint32_t OpenEvent(uint32_t classId, uint32_t spec, uint32_t mode, void (*handler)()) {
            register uint32_t FuncID asm("t1") = 0x08;
            
            __asm__ volatile("" : "=r"(FuncID) : "r"(FuncID));
            return __syscall_function_cast(Table_B, uint32_t(*)(uint32_t, uint32_t, uint32_t, void(*)()))(classId, spec, mode, handler);
        }

        static __always_inline int CloseEvent(uint32_t event) {
            register uint32_t FuncID asm("t1") = 0x09;
            
            __asm__ volatile("" : "=r"(FuncID) : "r"(FuncID));
            return __syscall_function_cast(Table_B, uint32_t(*)(uint32_t))(event);
        }

        static __always_inline int TestEvent(uint32_t event) {
            register uint32_t FuncID asm("t1") = 0x0B;
            
            __asm__ volatile("" : "=r"(FuncID) : "r"(FuncID));
            return __syscall_function_cast(Table_B, int (*)(uint32_t))(event);
        }

        static __always_inline int EnableEvent(uint32_t event) {
            register uint32_t FuncID asm("t1") = 0x0C;
            
            __asm__ volatile("" : "=r"(FuncID) : "r"(FuncID));
            return __syscall_function_cast(Table_B, int (*)(uint32_t))(event);
        }

        void printf(const char* txt, ...);
    }
}