isr.s

// Kernel stack for interrupt handling.
KERNEL_STACK = 0x80000
// GDT selectors.
KERNEL_DS = 0x10

// not USER stack yet
// USER_DS   = 0x23
USER_DS = 0x10

// Template for the Interrupt Service Routines.
.macro isrGenerate n
    .align 4
    .type isr\n, @function
    .global isr\n

    isr\n:
        // Push a dummy error code for interrupts that don't have one.
        .if (\n != 8 && !(\n >= 10 && \n <= 14) && \n != 17)
            push $0
        .endif
        push $\n       // Push the interrupt number.
        jmp isrCommon  // Jump to the common handler.
.endmacro

// Common code for all Interrupt Service Routines.
isrCommon:
    pusha  // Save the registers state.

    // Setup kernel data segment.
    mov $KERNEL_DS, %ax
    mov %ax, %ds
    mov %ax, %es

    // Save the pointer to the current context and switch to the kernel stack.
    mov %esp, context
    mov $KERNEL_STACK, %esp

    call interruptDispatch  // Handle the interrupt event.

    // Restore the pointer to the context (of a different thread, potentially).
    mov context, %esp

    // Setup user data segment.
    mov $USER_DS, %ax
    mov %ax, %ds
    mov %ax, %es


    popa          // Restore the registers state.
    add $8, %esp  // Remove interrupt number and error code from stack.
    iret
.type isrCommon, @function

// Exceptions.
isrGenerate 0
isrGenerate 1
isrGenerate 2
isrGenerate 3
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isrGenerate 31

// IRQs.
isrGenerate 32
isrGenerate 33
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isrGenerate 47

// Syscalls.
isrGenerate 128