Fusion_C and HTIMI

I'm using interslot call. In SetInterruptHandler() I install an "int-handler" (starting at inthandler_start: ) to page 3. That handler makes interslot call to the user code, that may reside even on page 0.

So I could skip that "int-handler" and use CALLF instead?

The thing I'm not sure about is, will it work, if the user code is near page-boundary? Normally it will be fine, when the hook is been called, page 0 is BIOS and page 1 and following are RAM, it doesn't matter where there user code is. But what if page 1 is some ROM?

Makes sense, for a library it is better, in my code I've preferred to move the function at startup using ldir for page 4 and used a simple call to get better performance.

I did something like this in a previous project:

unsigned char interruptRealloc[512];

// Program interrupt handler to call our routine first
void programInt(void)
{
__asm
    ; Disable interrupts, it will not be nice if an interrupt occurs before all
    ; was properly set
    DI
    ; Save the registers we are going to use
    PUSH BC
    PUSH DE
    PUSH HL
    ; This is the area where we are going to save the original interrupt handler
    ; Why? It is the beginning of the routine that is called before main is
    ; executed and it will not be called anymore, so we put it to good use
    ; First copy our interrupt routine to _interruptRealloc
    LD DE,#_interruptRealloc
    ; This is the address Z80 will call everytime interrupts are triggered
    LD HL,#_myIntHandler
    ; Counter of how many bytes need to be transferred
    LD BC,#_enterIntMode - _myIntHandler
    ; Copy data
    LDIR

    LD DE,#0x0100
    ; This is the address Z80 will call everytime interrupts are triggered
    LD HL,#0xFD9A
    ; Counter of how many bytes need to be transferred
    LD BC,#0x5
    ; Copy data
    LDIR
    ; HL changes after LDIR, so restore it to the interrupt handler address
    LD HL,#0xFD9A
    ; First we will put the JP command
    LD B,#0xC3
    ; Now, put that into the memory
    LD (HL),B
    ; Increment our memory copy address
    INC HL
    ; Load the memory address of our function in BC pair of registers
    LD BC,#_interruptRealloc
    ; Move the LSB of the address just after JP
    LD (HL),C
    ; Increment our memory copy address
    INC HL
    ; Move the MSB of the address after the LSB
    LD (HL),B
    ; We are done, restore registers we have used
    POP HL
    POP DE
    POP BC
    ; Enable interrupts again
    EI
__endasm;
}

// Restore interrupt handler so we won't be called before processing interrupt
// Useful when exiting the program, as once our program no longer runs, it won't
// proccess anything and interrupts will go crazy if handler is not restored
void restoreInt(void)
{
__asm
    ; Disable interrupts, it will not be nice if an interrupt occurs before all
    ; was properly set
    DI
    ; Save the registers we are going to use
    PUSH BC
    PUSH DE
    PUSH HL
    ; This is the area where we are going to restore the original interrupt handler
    LD DE,#0xFD9A
    ; This is the address where the original handler was saved
    LD HL,#0x0100
    ; 5 bytes
    LD BC,#0x5
    ; copy it
    LDIR
    ; We are done, restore registers we have used
    POP HL
    POP DE
    POP BC
    ; Enable interrupts again
    EI
__endasm;
}

void myIntHandler(void) __naked
{
__asm
    ; Interrupt Routine goes here
    ret
__endasm;
}

void enterIntMode(void)
{

interruptRealloc is just to make sure the interrupt is in place other than page 0, you might do things differently to achieve this (compile order, etc) and skip reallocating the interrupt, that worked for me at that time, perhaps nowadays I would do it differently...

By the way, this code uses the general interrupt, not the VDP interrupt...

Hello,

I'm having trouble integrating a proper interrupt system into Fusion-C.
I do not have enough knowledge on the subject.

Is one of you have some code I can add to Fusion-c?
Ducasp? Can II use your? Do you have example of usage of your code?

Thank you.
I 'm waiting for you...