86Box/src/pic.c

#include "ibm.h"
#include "io.h"
#include "pci.h"
#include "pic.h"
#include "pit.h"


int output;
int intclear;
int keywaiting=0;
int pic_intpending;
PIC pic, pic2;
uint16_t pic_current;


void pic_updatepending()
{
	uint16_t temp_pending = 0;
	if (AT)
	{
	        if ((pic2.pend&~pic2.mask)&~pic2.mask2)
        	        pic.pend |= pic.icw3;
	        else
        	        pic.pend &= ~pic.icw3;
	}
        pic_intpending = (pic.pend & ~pic.mask) & ~pic.mask2;
	if (AT)
	{
	        if (!((pic.mask | pic.mask2) & pic.icw3))
		{
			temp_pending = ((pic2.pend&~pic2.mask)&~pic2.mask2);
			temp_pending <<= 8;
        	        pic_intpending |= temp_pending;
		}
	}
/*        pclog("pic_intpending = %i  %02X %02X %02X %02X\n", pic_intpending, pic.ins, pic.pend, pic.mask, pic.mask2);
        pclog("                    %02X %02X %02X %02X %i %i\n", pic2.ins, pic2.pend, pic2.mask, pic2.mask2, ((pic.mask | pic.mask2) & (1 << 2)), ((pic2.pend&~pic2.mask)&~pic2.mask2)); */
}


void pic_reset()
{
        pic.icw=0;
        pic.mask=0xFF;
        pic.mask2=0;
        pic.pend=pic.ins=0;
        pic.vector=8;
        pic.read=1;
        pic2.icw=0;
        pic2.mask=0xFF;
        pic.mask2=0;
        pic2.pend=pic2.ins=0;
        pic_intpending = 0;
}

void pic_update_mask(uint8_t *mask, uint8_t ins)
{
        int c;
        *mask = 0;
        for (c = 0; c < 8; c++)
        {
                if (ins & (1 << c))
                {
                        *mask = 0xff << c;
                        return;
                }
        }
}

static int picint_is_level(uint16_t irq)
{
	if (PCI)
	{
		return pci_irq_is_level(irq);
	}
	else
	{
		if (irq < 8)
		{
			return (pic.icw1 & 8) ? 1 : 0;
		}
		else
		{
			return (pic2.icw1 & 8) ? 1 : 0;
		}
	}
}

static void pic_autoeoi()
{
        int c;
        
        for (c=0;c<8;c++)
        {
                if (pic.ins&(1<<c))
                {
                        pic.ins&=~(1<<c);
                        pic_update_mask(&pic.mask2, pic.ins);

			if (AT)
			{
	                        if (((1 << c) == pic.icw3) && (pic2.pend&~pic2.mask)&~pic2.mask2)
	                                pic.pend |= pic.icw3;
			}

			if ((pic_current & (1 << c)) && picint_is_level(c))
			{
				if (((1 << c) != pic.icw3) || !AT)
				{
					pic.pend |= 1 << c;
				}
			}

                        pic_updatepending();
                        return;
                }
        }
}

void pic_write(uint16_t addr, uint8_t val, void *priv)
{
        int c;
        if (addr&1)
        {
                switch (pic.icw)
                {
                        case 0: /*OCW1*/
                        pic.mask=val;
                        pic_updatepending();
                        break;
                        case 1: /*ICW2*/
                        pic.vector=val&0xF8;
                        if (pic.icw1&2) pic.icw=3;
                        else            pic.icw=2;
                        break;
                        case 2: /*ICW3*/
                        pic.icw3 = val;
			pclog("PIC1 ICW3 now %02X\n", val);
                        if (pic.icw1&1) pic.icw=3;
                        else            pic.icw=0;
                        break;
                        case 3: /*ICW4*/
                        pic.icw4 = val;
                        pic.icw=0;
                        break;
                }
        }
        else
        {
                if (val&16) /*ICW1*/
                {
                        pic.mask = 0;
                        pic.mask2=0;
                        pic.icw=1;
                        pic.icw1=val;
                        pic.ins = 0;
                        pic_updatepending();
                }
                else if (!(val&8)) /*OCW2*/
                {
                        if ((val&0xE0)==0x60)
                        {
                                pic.ins&=~(1<<(val&7));
                                pic_update_mask(&pic.mask2, pic.ins);
				if (AT)
				{
	                                if (((val&7) == pic2.icw3) && (pic2.pend&~pic2.mask)&~pic2.mask2)
        	                                pic.pend |= pic.icw3;
				}

				if ((pic_current & (1 << (val & 7))) && picint_is_level(val & 7))
				{
					if ((((1 << (val & 7)) != pic.icw3) || !AT))
					{
						pic.pend |= 1 << (val & 7);
					}
				}

                                pic_updatepending();
                        }
                        else
                        {
                                for (c=0;c<8;c++)
                                {
                                        if (pic.ins&(1<<c))
                                        {
                                                pic.ins&=~(1<<c);
                                                pic_update_mask(&pic.mask2, pic.ins);

						if (AT)
						{
	                                                if (((1 << c) == pic.icw3) && (pic2.pend&~pic2.mask)&~pic2.mask2)
        	                                                pic.pend |= pic.icw3;
						}

						if ((pic_current & (1 << c)) && picint_is_level(c))
						{
							if ((((1 << c) != pic.icw3) || !AT))
							{
								pic.pend |= 1 << c;
							}
						}

                                                if (c==1 && keywaiting)
                                                {
                                                        intclear&=~1;
                                                }
                                                pic_updatepending();
                                                return;
                                        }
                                }
                        }
                }
                else               /*OCW3*/
                {
                        if (val&2) pic.read=(val&1);
                        if (val&0x40) { }
                }
        }
}

uint8_t pic_read(uint16_t addr, void *priv)
{
        if (addr&1) { /*pclog("Read PIC mask %02X\n",pic.mask);*/ return pic.mask; }
        if (pic.read) { /*pclog("Read PIC ins %02X\n",pic.ins);*/ return pic.ins | (pic2.ins ? 4 : 0); }
        return pic.pend;
}

void pic_init()
{
        io_sethandler(0x0020, 0x0002, pic_read, NULL, NULL, pic_write, NULL, NULL, NULL);
}

static void pic2_autoeoi()
{
        int c;
        
        for (c = 0; c < 8; c++)
        {
                if (pic2.ins & (1 << c))
                {
                        pic2.ins &= ~(1 << c);
                        pic_update_mask(&pic2.mask2, pic2.ins);

			if (pic_current & (0x100 << c) && picint_is_level(c + 8))
			{
				pic2.pend |= (1 << c);
				pic.pend |= (1 << pic2.icw3);
			}

                        pic_updatepending();
                        return;
                }
        }
}

void pic2_write(uint16_t addr, uint8_t val, void *priv)
{
        int c;
        if (addr&1)
        {
                switch (pic2.icw)
                {
                        case 0: /*OCW1*/
                        pic2.mask=val;
                        pic_updatepending();
                        break;
                        case 1: /*ICW2*/
                        pic2.vector=val&0xF8;
			pclog("PIC2 vector now: %02X\n", pic2.vector);
                        if (pic2.icw1&2) pic2.icw=3;
                        else            pic2.icw=2;
                        break;
                        case 2: /*ICW3*/
                        pic2.icw3 = val;
			pclog("PIC2 ICW3 now %02X\n", val);
                        if (pic2.icw1&1) pic2.icw=3;
                        else            pic2.icw=0;
                        break;
                        case 3: /*ICW4*/
                        pic2.icw4 = val;
                        pic2.icw=0;
                        break;
                }
        }
        else
        {
                if (val&16) /*ICW1*/
                {
                        pic2.mask = 0;
                        pic2.mask2=0;
                        pic2.icw=1;
                        pic2.icw1=val;
                        pic2.ins = 0;
                        pic_updatepending();
                }
                else if (!(val&8)) /*OCW2*/
                {
                        if ((val&0xE0)==0x60)
                        {
                                pic2.ins&=~(1<<(val&7));
                                pic_update_mask(&pic2.mask2, pic2.ins);

				if (pic_current & (0x100 << (val & 7)) && picint_is_level((val & 7) + 8))
				{
					pic2.pend |= (1 << (val & 7));
					pic.pend |= (1 << pic2.icw3);
				}

                                pic_updatepending();
                        }
                        else
                        {
                                for (c=0;c<8;c++)
                                {
                                        if (pic2.ins&(1<<c))
                                        {
                                                pic2.ins &= ~(1<<c);
                                                pic_update_mask(&pic2.mask2, pic2.ins);

						if (pic_current & (0x100 << c) && picint_is_level(c + 8))
						{
							pic2.pend |= (1 << c);
							pic.pend |= (1 << pic2.icw3);
						}

                                                pic_updatepending();
                                                return;
                                        }
                                }
                        }
                }
                else               /*OCW3*/
                {
                        if (val&2) pic2.read=(val&1);
                }
        }
}

uint8_t pic2_read(uint16_t addr, void *priv)
{
        if (addr&1) { /*pclog("Read PIC2 mask %02X %04X:%08X\n",pic2.mask,CS,pc);*/ return pic2.mask; }
        if (pic2.read) { /*pclog("Read PIC2 ins %02X %04X:%08X\n",pic2.ins,CS,pc);*/ return pic2.ins; }
        /*pclog("Read PIC2 pend %02X %04X:%08X\n",pic2.pend,CS,pc);*/
        return pic2.pend;
}

void pic2_init()
{
        io_sethandler(0x00a0, 0x0002, pic2_read, NULL, NULL, pic2_write, NULL, NULL, NULL);
}


void clearpic()
{
        pic.pend=pic.ins=pic_current=0;
        pic_updatepending();
}

void picint_common(uint16_t num, int level)
{
        int c = 0;

        if (!num)
	{
		/* pclog("Attempting to raise null IRQ\n"); */
                return;
	}

        if (AT && (num == pic.icw3) && (pic.icw3 == 4))
	{
                num = 1 << 9;
	}

        while (!(num & (1 << c))) c++;

	if (AT && (num == pic.icw3) && (pic.icw3 != 4))
	{
		/* pclog("Attempting to raise cascaded IRQ %i\n"); */
		return;
	}

        if (!(pic_current & num) || !level)
        {
		/* pclog("Raising IRQ %i\n", c); */

		if (level)
		{
	                pic_current |= num;
		}

	        if (num>0xFF)
        	{
			if (!AT)
			{
				return;
			}

			pic2.pend|=(num>>8);
			if ((pic2.pend&~pic2.mask)&~pic2.mask2)
			{
				pic.pend |= (1 << pic2.icw3);
			}
	        }
	        else
        	{
	                pic.pend|=num;
        	}
	        pic_updatepending();
	}
}

void picint(uint16_t num)
{
	picint_common(num, 0);
}

void picintlevel(uint16_t num)
{
	picint_common(num, 1);
}

void picintc(uint16_t num)
{
        int c = 0;

        if (!num)
	{
		/* pclog("Attempting to lower null IRQ\n"); */
                return;
	}

        if (AT && (num == pic.icw3) && (pic.icw3 == 4))
	{
                num = 1 << 9;
	}

        while (!(num & (1 << c))) c++;

	if (AT && (num == pic.icw3) && (pic.icw3 != 4))
	{
		/* pclog("Attempting to lower cascaded IRQ %i\n"); */
		return;
	}

	if (pic_current & num)
	{
	        pic_current &= ~num;
	}

	/* pclog("Lowering IRQ %i\n", c); */

        if (num > 0xff)
        {
		if (!AT)
		{
			return;
		}

                pic2.pend &= ~(num >> 8);
                if (!((pic2.pend&~pic2.mask)&~pic2.mask2))
		{
                        pic.pend &= ~(1 << pic2.icw3);
		}
        }
        else
        {
                pic.pend&=~num;
        }
        pic_updatepending();
}

/* TODO: Verify this whole level-edge thing... edge/level mode is supposedly handled by bit 3 of ICW1,
	 but the PIIX spec mandates it being able to be edge/level per IRQ... maybe the PCI-era on-board
	 PIC ignores bit 3 of ICW1 but instead uses whatever is set in ELCR?

   Edit: Yes, the PIIX (and I suppose also the SIO) disables bit 3 of ICW1 and instead, uses the ELCR.

	 Also, shouldn't there be only one picint(), and then edge/level is handled on processing? */

static uint8_t pic_process_interrupt(PIC* target_pic, int c)
{
	uint8_t pending = target_pic->pend & ~target_pic->mask;

	int pic_int = c & 7;
	int pic_int_num = 1 << pic_int;

	/* int pic_cur_num = 1 << c; */

       	if (pending & pic_int_num)
	{
		target_pic->pend &= ~pic_int_num;
		target_pic->ins |= pic_int_num;
		pic_update_mask(&target_pic->mask2, target_pic->ins);

		if (c >= 8)
		{
			pic.ins |= (1 << pic2.icw3); /*Cascade IRQ*/
			pic_update_mask(&pic.mask2, pic.ins);
		}

		pic_updatepending();

		if (target_pic->icw4 & 0x02)
		{
			(c >= 8) ? pic2_autoeoi() : pic_autoeoi();
		}

		if (!c)
		{
			pit_set_gate(&pit2, 0, 0);
		}

		return pic_int + target_pic->vector;
	}
	else
	{
		return 0xFF;
	}
}

uint8_t picinterrupt()
{
        int c, d;
	uint8_t ret;

        for (c = 0; c <= 7; c++)
        {
       	        if (AT && ((1 << c) == pic.icw3))
		{
        	        for (d = 8; d <= 15; d++)
	                {
				ret = pic_process_interrupt(&pic2, d);
				if (ret != 0xFF)  return ret;
	                }
		}
		else
                {
			ret = pic_process_interrupt(&pic, c);
			if (ret != 0xFF)  return ret;
                }
        }
        return 0xFF;
}

void dumppic()
{
        pclog("PIC1 : MASK %02X PEND %02X INS %02X LEVEL %02X VECTOR %02X CASCADE %02X\n", pic.mask, pic.pend, pic.ins, (pic.icw1 & 8) ? 1 : 0, pic.vector, pic.icw3);
	if (AT)
	{
	        pclog("PIC2 : MASK %02X PEND %02X INS %02X LEVEL %02X VECTOR %02X CASCADE %02X\n", pic2.mask, pic2.pend, pic2.ins, (pic2.icw1 & 8) ? 1 : 0, pic2.vector, pic2.icw3);
	}
}