// hal_pci.c - PCI configuration space via Mechanism 1 port I/O
#include <stdint.h>
#include <hal_api.h>

#define PCI_CONFIG_ADDR  0xCF8
#define PCI_CONFIG_DATA  0xCFC

static uint32_t MakeAddr(uint8_t bus, uint8_t dev, uint8_t fn, uint8_t reg) {
    return 0x80000000UL
         | ((uint32_t)bus << 16)
         | ((uint32_t)(dev & 0x1F) << 11)
         | ((uint32_t)(fn  & 0x07) <<  8)
         | (reg & 0xFC);
}

static uint32_t PciRead32(uint8_t bus, uint8_t dev, uint8_t fn, uint8_t reg) {
    __outdword(PCI_CONFIG_ADDR, MakeAddr(bus, dev, fn, reg));
    return __indword(PCI_CONFIG_DATA);
}

static void PciWrite32(uint8_t bus, uint8_t dev, uint8_t fn,
                       uint8_t reg, uint32_t val) {
    __outdword(PCI_CONFIG_ADDR, MakeAddr(bus, dev, fn, reg));
    __outdword(PCI_CONFIG_DATA, val);
}

static bool PciFindDevice(uint16_t vendor, uint16_t device,
                          uint8_t* outBus, uint8_t* outDev, uint8_t* outFn) {
    for (int bus = 0; bus < 256; bus++)
        for (int dev = 0; dev < 32; dev++)
            for (int fn = 0; fn < 8; fn++) {
                uint32_t id = PciRead32((uint8_t)bus, (uint8_t)dev, (uint8_t)fn, 0);
                if ((id & 0xFFFF) == vendor && (id >> 16) == device) {
                    *outBus = (uint8_t)bus; *outDev = (uint8_t)dev; *outFn = (uint8_t)fn;
                    return true;
                }
            }
    return false;
}

static bool PciFindClass(uint8_t classCode, uint8_t subclass,
                         uint8_t* outBus, uint8_t* outDev, uint8_t* outFn) {
    for (int bus = 0; bus < 256; bus++)
        for (int dev = 0; dev < 32; dev++)
            for (int fn = 0; fn < 8; fn++) {
                uint32_t id = PciRead32((uint8_t)bus,(uint8_t)dev,(uint8_t)fn,0);
                if ((id & 0xFFFF) == 0xFFFF) continue;   // no device
                uint32_t cc = PciRead32((uint8_t)bus,(uint8_t)dev,(uint8_t)fn,8);
                if (((cc >> 24) & 0xFF) == classCode &&
                    ((cc >> 16) & 0xFF) == subclass) {
                    *outBus = (uint8_t)bus; *outDev = (uint8_t)dev; *outFn = (uint8_t)fn;
                    return true;
                }
            }
    return false;
}

static uint8_t PciGetIrqLine(uint8_t bus, uint8_t dev, uint8_t fn) {
    // PCI config register 0x3C: byte 0 = IRQ line, byte 1 = IRQ pin
    uint32_t val = PciRead32(bus, dev, fn, 0x3C);
    return (uint8_t)(val & 0xFF);   // 0xFF = not connected
}

void HalPciInitialize(HAL_PCI* out) {
    out->Read32  = PciRead32;
    out->Write32 = PciWrite32;
    out->FindDevice    = PciFindDevice;
    out->FindClass     = PciFindClass;
    out->GetIrqLine    = PciGetIrqLine;
}