Ringbuffer: add null checks and more const

Makefile

@@ -1,8 +1,8 @@
 run: bin
-	qemu-system-i386 -drive format=raw,file=target/boot.bin -monitor stdio
+	qemu-system-i386 -vga std -nodefaults -drive format=raw,file=target/boot.bin -monitor stdio -device e1000,netdev=u1,mac=aa:bb:cc:dd:ee:ff -object filter-dump,id=f1,netdev=u1,file=/tmp/dump.pcap -netdev tap,id=u1,ifname=tap0,script=no,downscript=no
 
 run_kernelonly: compile_kernel
-	qemu-system-i386 -kernel target/kernel/kernel.bin -monitor stdio
+	qemu-system-i386 -kernel target/kernel/kernel.bin -monitor stdio -vga std -nodefaults -device e1000,netdev=u1,mac=aa:bb:cc:dd:ee:ff -object filter-dump,id=f1,netdev=u1,file=/tmp/dump.dat -netdev tap,id=u1,ifname=tap0,script=no,downscript=no
 
 debug_kernel: compile_kernel
 	qemu-system-i386 -s -S -kernel target/kernel/kernel.bin

README.md

@@ -18,6 +18,8 @@ If you run `make bin`, it will generate `target/boot.bin`, this is a binary file
 In case there are errors in the bootloader you can use `make compile_kernel` to only compile the kernel.
 
 To run TABS in the qemu simulator run `make run`.
+To test the operating system in QEMU, first set up a tap interface with the `create_tap.sh` script,
+then run `make run` or `make run_kernelonly`.
 
 ## Bootloader
 
@@ -45,5 +47,8 @@ The kernel is based on [the bare bones kernel from the OSDev wiki](https://wiki.
 - [ ] Running executables from filesystem
 - [ ] Better memory management
 - [ ] Better shell
+- [X] A driver for E1000-type network cards
+  - [X] sending packets
+  - [X] receiving packets
 
 As a test, I've implemented day 1 of [advent of code](https://adventofcode.com/) on the [AoC branch](https://github.com/Robbe7730/RoBoot/tree/AoC).

create_tap.sh

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+sudo ip tuntap add dev tap0 mode tap
+sudo ip link set up dev tap0
+sudo chown $USER tap0

kernel/drivers/networking/e1000.c

@@ -0,0 +1,334 @@
+#ifndef DRIVERS_NETWORKING_E1000_C
+#define DRIVERS_NETWORKING_E1000_C
+
+#include "../../inline_asm.c"
+#include "../pci/pci.c"
+
+#define E1000_NUM_RX_DESC 32
+#define E1000_NUM_TX_DESC 8
+
+static uint32_t e1000_device_pci = 0x00000000;
+static uintptr_t mem_base = 0;
+static int has_eeprom = 0;
+static uint8_t e1000_mac[6];
+
+// Aligned alloc
+void* valloc(unsigned int size, int i) {
+  uint32_t addr = (uint32_t) alloc(size + (1 << i));
+  addr = (((addr - 1) >> i) + 1 ) << i;
+  return (void*) addr;
+}
+
+struct rx_desc {
+	volatile uint64_t addr;
+	volatile uint16_t length;
+	volatile uint16_t checksum;
+	volatile uint8_t  status;
+	volatile uint8_t  errors;
+	volatile uint16_t special;
+} __attribute__((packed));
+
+struct tx_desc {
+	volatile uint64_t addr;
+	volatile uint16_t length;
+	volatile uint8_t  cso;
+	volatile uint8_t  cmd;
+	volatile uint8_t  status;
+	volatile uint8_t  css;
+	volatile uint16_t special;
+} __attribute__((packed));
+
+static uint8_t * rx_virt[E1000_NUM_RX_DESC];
+static uint8_t * tx_virt[E1000_NUM_TX_DESC];
+static struct rx_desc * rx;
+static struct tx_desc * tx;
+static uintptr_t rx_phys;
+static uintptr_t tx_phys;
+
+#define E1000_REG_CTRL       0x0000
+#define E1000_REG_STATUS     0x0008
+#define E1000_REG_EEPROM     0x0014
+#define E1000_REG_CTRL_EXT   0x0018
+
+#define E1000_REG_RCTRL      0x0100
+#define E1000_REG_RXDESCLO   0x2800
+#define E1000_REG_RXDESCHI   0x2804
+#define E1000_REG_RXDESCLEN  0x2808
+#define E1000_REG_RXDESCHEAD 0x2810
+#define E1000_REG_RXDESCTAIL 0x2818
+
+#define E1000_REG_TCTRL      0x0400
+#define E1000_REG_TXDESCLO   0x3800
+#define E1000_REG_TXDESCHI   0x3804
+#define E1000_REG_TXDESCLEN  0x3808
+#define E1000_REG_TXDESCHEAD 0x3810
+#define E1000_REG_TXDESCTAIL 0x3818
+
+#define E1000_REG_RXADDR     0x5400
+
+#define RCTL_EN                         (1 << 1)    /* Receiver Enable */
+#define RCTL_SBP                        (1 << 2)    /* Store Bad Packets */
+#define RCTL_UPE                        (1 << 3)    /* Unicast Promiscuous Enabled */
+#define RCTL_MPE                        (1 << 4)    /* Multicast Promiscuous Enabled */
+#define RCTL_LPE                        (1 << 5)    /* Long Packet Reception Enable */
+#define RCTL_LBM_NONE                   (0 << 6)    /* No Loopback */
+#define RCTL_LBM_PHY                    (3 << 6)    /* PHY or external SerDesc loopback */
+#define RTCL_RDMTS_HALF                 (0 << 8)    /* Free Buffer Threshold is 1/2 of RDLEN */
+#define RTCL_RDMTS_QUARTER              (1 << 8)    /* Free Buffer Threshold is 1/4 of RDLEN */
+#define RTCL_RDMTS_EIGHTH               (2 << 8)    /* Free Buffer Threshold is 1/8 of RDLEN */
+#define RCTL_MO_36                      (0 << 12)   /* Multicast Offset - bits 47:36 */
+#define RCTL_MO_35                      (1 << 12)   /* Multicast Offset - bits 46:35 */
+#define RCTL_MO_34                      (2 << 12)   /* Multicast Offset - bits 45:34 */
+#define RCTL_MO_32                      (3 << 12)   /* Multicast Offset - bits 43:32 */
+#define RCTL_BAM                        (1 << 15)   /* Broadcast Accept Mode */
+#define RCTL_VFE                        (1 << 18)   /* VLAN Filter Enable */
+#define RCTL_CFIEN                      (1 << 19)   /* Canonical Form Indicator Enable */
+#define RCTL_CFI                        (1 << 20)   /* Canonical Form Indicator Bit Value */
+#define RCTL_DPF                        (1 << 22)   /* Discard Pause Frames */
+#define RCTL_PMCF                       (1 << 23)   /* Pass MAC Control Frames */
+#define RCTL_SECRC                      (1 << 26)   /* Strip Ethernet CRC */
+
+#define RCTL_BSIZE_256                  (3 << 16)
+#define RCTL_BSIZE_512                  (2 << 16)
+#define RCTL_BSIZE_1024                 (1 << 16)
+#define RCTL_BSIZE_2048                 (0 << 16)
+#define RCTL_BSIZE_4096                 ((3 << 16) | (1 << 25))
+#define RCTL_BSIZE_8192                 ((2 << 16) | (1 << 25))
+#define RCTL_BSIZE_16384                ((1 << 16) | (1 << 25))
+
+#define TCTL_EN                         (1 << 1)    /* Transmit Enable */
+#define TCTL_PSP                        (1 << 3)    /* Pad Short Packets */
+#define TCTL_CT_SHIFT                   4           /* Collision Threshold */
+#define TCTL_COLD_SHIFT                 12          /* Collision Distance */
+#define TCTL_SWXOFF                     (1 << 22)   /* Software XOFF Transmission */
+#define TCTL_RTLC                       (1 << 24)   /* Re-transmit on Late Collision */
+
+#define CMD_EOP                         (1 << 0)    /* End of Packet */
+#define CMD_IFCS                        (1 << 1)    /* Insert FCS */
+#define CMD_IC                          (1 << 2)    /* Insert Checksum */
+#define CMD_RS                          (1 << 3)    /* Report Status */
+#define CMD_RPS                         (1 << 4)    /* Report Packet Sent */
+#define CMD_VLE                         (1 << 6)    /* VLAN Packet Enable */
+#define CMD_IDE                         (1 << 7)    /* Interrupt Delay Enable */
+
+#define RX_STATUS_DD										(1 << 0)    /* Descriptor done */
+
+#define STATUS_LINK_UP                  (1 << 1)    /* Link Up */
+
+static void write_command(uint16_t addr, uint32_t val) {
+	(*((volatile uint32_t*)(mem_base + addr))) = val;
+}
+
+static uint32_t read_command(uint16_t addr) {
+	return *((volatile uint32_t*)(mem_base + addr));
+}
+
+static int eeprom_detect(void) {
+
+	write_command(E1000_REG_EEPROM, 1);
+
+	for (int i = 0; i < 100000 && !has_eeprom; ++i) {
+		uint32_t val = read_command(E1000_REG_EEPROM);
+		if (val & 0x10) has_eeprom = 1;
+	}
+
+	return 0;
+}
+
+static uint16_t eeprom_read(uint8_t addr) {
+	uint32_t temp = 0;
+	write_command(E1000_REG_EEPROM, 1 | ((uint32_t)(addr) << 8));
+	while (!((temp = read_command(E1000_REG_EEPROM)) & (1 << 4)));
+	return (uint16_t)((temp >> 16) & 0xFFFF);
+}
+
+
+static void find_e1000(uint32_t device, uint16_t vendorid, uint16_t deviceid, void * extra) {
+	if ((vendorid == 0x8086) && (deviceid == 0x100e || deviceid == 0x1004 || deviceid == 0x100f || deviceid == 0x10ea)) {
+		*((uint32_t *)extra) = device;
+	}
+}
+
+static void write_mac(void) {
+
+	uint32_t low;
+	uint32_t high;
+
+	memcpy(&low, &e1000_mac[0], 4);
+	memcpy(&high,&e1000_mac[4], 2);
+	memset((uint8_t *)&high + 2, 0, 2);
+	high |= 0x80000000;
+
+	write_command(E1000_REG_RXADDR + 0, low);
+	write_command(E1000_REG_RXADDR + 4, high);
+}
+
+static void read_mac(void) {
+	if (has_eeprom) {
+		for (int i = 0; i < 3; i++) {
+			uint32_t part = eeprom_read(i);
+			e1000_mac[2*i] = part & 0xFF;
+			e1000_mac[2*i + 1] = (part >> 8) & 0xFF;
+		}
+	} else {
+		uint8_t* mac_addr = (uint8_t*)(mem_base + E1000_REG_RXADDR);
+		for (int i = 0; i < 6; ++i) {
+			e1000_mac[i] = mac_addr[i];
+		}
+	}
+}
+
+
+// Receives a packet, returning the size of the packet or 0 if no packet was received
+//  User is responsible for freeing the buffer that we will allocate
+static size_t receive_packet(uint8_t** payload) {
+	uint32_t rx_index = read_command(E1000_REG_RXDESCTAIL);
+	if (rx_index == read_command(E1000_REG_RXDESCHEAD)) {
+		// head == tail, so the queue is empty
+		return 0;
+	}
+
+	rx_index = (rx_index + 1) % E1000_NUM_RX_DESC;
+	uint32_t packetstatus = rx[rx_index].status;
+	if (!(packetstatus & (RX_STATUS_DD))) {
+		// The network card isn't done receiving this packet
+		return 0;
+	}
+	// Normally, we would have to check if this is the end of the packet, but
+	//  since we receive in chunks of 2048, an ethernet frame always fits in one chunk
+	uint8_t* packet_address = (uint8_t*) rx_virt[rx_index];
+	size_t size = (size_t) rx[rx_index].length;
+	void* user_packet = alloc(size);
+	memcpy(user_packet, packet_address, size);
+
+	// Set the status to done
+	rx[rx_index].status = 0;
+
+	// Update the network card's tail
+	write_command(E1000_REG_RXDESCTAIL, rx_index);
+	*payload = user_packet;
+	return size;
+}
+
+static void send_packet(uint8_t* payload, size_t payload_size) {
+	uint32_t tx_index = read_command(E1000_REG_TXDESCTAIL);
+
+	memcpy(tx_virt[tx_index], payload, payload_size);
+	tx[tx_index].length = payload_size;
+	// End Of Packet, let hardware generate checksum
+	tx[tx_index].cmd = CMD_EOP | CMD_IFCS;
+	tx[tx_index].status = 0;
+
+	tx_index = (tx_index + 1) % E1000_NUM_TX_DESC;
+	write_command(E1000_REG_TXDESCTAIL, tx_index);
+}
+
+static void init_rx(void) {
+	// Set physical address of receive FIFO
+	write_command(E1000_REG_RXDESCLO, rx_phys);
+	write_command(E1000_REG_RXDESCHI, 0);
+
+	write_command(E1000_REG_RXDESCLEN, E1000_NUM_RX_DESC * sizeof(struct rx_desc));
+
+	// Initialize head and tail of receive FIFO
+	write_command(E1000_REG_RXDESCHEAD, 0);
+	write_command(E1000_REG_RXDESCTAIL, E1000_NUM_RX_DESC - 1);
+
+	// Enable receiving, receive packets of up to 2048, allow receiving broadcast packets
+	write_command(E1000_REG_RCTRL,
+		RCTL_EN  | RCTL_BSIZE_2048 | RCTL_BAM |
+		(read_command(E1000_REG_RCTRL)));
+
+}
+
+static void init_tx(void) {
+
+	// Set physical address of transmit FIFO
+	write_command(E1000_REG_TXDESCLO, tx_phys);
+	write_command(E1000_REG_TXDESCHI, 0);
+
+	write_command(E1000_REG_TXDESCLEN, E1000_NUM_TX_DESC * sizeof(struct tx_desc));
+
+	// Initialize head and tail of transmit FIFO
+	write_command(E1000_REG_TXDESCHEAD, 0);
+	write_command(E1000_REG_TXDESCTAIL, 0);
+
+	// Enable transmitting, Pad Short Packets
+	write_command(E1000_REG_TCTRL,
+		TCTL_EN |
+		TCTL_PSP |
+		read_command(E1000_REG_TCTRL));
+}
+
+static int e1000_init_main(void) {
+	pci_scan(&find_e1000, -1, &e1000_device_pci);
+
+	if (!e1000_device_pci) {
+		terminal_writestring("No e1000 device found.");
+		return 1;
+	}
+
+	mem_base  = pci_read_field(e1000_device_pci, PCI_BAR0, 4) & 0xFFFFFFF0;
+
+	// TODO mark page as cache-disabled
+
+	// TODO shrink network buffer size to RCTL_BSIZE_2048
+	// TODO align to paragraph instead of to page
+
+	// We don't do paging, so the virtual address = the physical address
+	rx = valloc(sizeof(struct rx_desc) * E1000_NUM_RX_DESC + 16, 12);
+	rx_phys = (uintptr_t) rx;
+	for (int i = 0; i < E1000_NUM_RX_DESC; i++) {
+		// Allocate a 2048-sized piece of memory, aligned (so the last 4 bits are 0)
+		rx_virt[i] = valloc(2048, 4);
+		rx[i].addr = (uintptr_t) rx_virt[i];
+		rx[i].status = 0;
+	}
+
+  tx = valloc(sizeof(struct tx_desc) * E1000_NUM_TX_DESC + 16, 12);
+  tx_phys = (uintptr_t) tx;
+	for (int i = 0; i < E1000_NUM_TX_DESC; i++) {
+		tx_virt[i] = valloc(2048, 4);
+    tx[i].addr = (uintptr_t) tx_virt[i];
+		tx[i].status = 0;
+		tx[i].cmd = (1 << 0);
+	}
+
+	// Enable PCI bus mastering
+	uint16_t command_reg = pci_read_field(e1000_device_pci, PCI_COMMAND, 2);
+	command_reg |= (1 << 2);
+	command_reg |= (1 << 0);
+	pci_write_field(e1000_device_pci, PCI_COMMAND, 2, command_reg);
+
+	eeprom_detect();
+
+	terminal_writestring("EEPROM=");
+	terminal_writeint(has_eeprom, 10);
+
+	read_mac();
+	terminal_writestring(" MAC = ");
+	terminal_writeint(e1000_mac[0], 16);
+	terminal_writeint(e1000_mac[1], 16);
+	terminal_writeint(e1000_mac[2], 16);
+	terminal_writeint(e1000_mac[3], 16);
+	terminal_writeint(e1000_mac[4], 16);
+	terminal_writeint(e1000_mac[5], 16);
+	terminal_writestring("\n");
+	write_mac();
+
+	init_rx();
+	init_tx();
+
+	int networkstatus = read_command(E1000_REG_STATUS);
+
+  terminal_writestring("Network is ");
+	if (networkstatus) {
+		terminal_writestring("up!\n");
+	} else {
+		terminal_writestring("down :/ \n");
+	}
+
+	return 0;
+}
+
+#endif // DRIVERS_NETWORKING_E1000_C

kernel/drivers/networking/network.c

@@ -0,0 +1,47 @@
+#ifndef DRIVERS_NETWORKING_NETWORK_C
+#define DRIVERS_NETWORKING_NETWORK_C
+
+#include "e1000.c"
+#include "../../memory.c"
+
+uint8_t* create_packet(uint8_t dest[6], uint8_t src[6], uint8_t type[2], uint8_t* content, int contentlength) {
+  uint8_t* returnbuffer = alloc(6 + 6 + 2 + contentlength);
+  memcpy(returnbuffer, dest, 6);
+  memcpy(returnbuffer + 6, src, 6);
+  memcpy(returnbuffer + 6 + 6, type, 2);
+  memcpy(returnbuffer + 6 + 6 + 2, content, contentlength);
+  return returnbuffer;
+}
+
+void network_init() {
+
+  uint8_t dest[6] = {0x11, 0x22, 0x33, 0x44, 0x55, 0x66};
+  uint8_t src[6] = {0x1a, 0x2b, 0x3c, 0x4d, 0x5e, 0x6f};
+  uint8_t type[2] = {0x69, 0x69};
+
+  e1000_init_main();
+
+  for (int i = 0; i < 3; i++) {
+    uint8_t* packet = create_packet(dest, src, type, (uint8_t*) "Zulu Echo Uniform Sierra Whiskey Papa India", 43);
+
+    send_packet(packet, 6 + 6 + 2 + 43);
+    // TODO free(packet)
+  }
+
+  uint8_t* received_packet;
+  while (1) {
+    size_t s = receive_packet(&received_packet);
+    if (s) {
+      terminal_writeint(s, 10);
+      terminal_writestring("  received packet \n");
+      for (size_t i = 0; i < s; i++) {
+        terminal_putchar(received_packet[i]);
+      }
+      // TODO free(*received_packet)
+      break;
+    }
+  }
+
+}
+
+#endif // DRIVERS_NETWORKING_NETWORK_C

kernel/drivers/pci/pci.c

@@ -0,0 +1,196 @@
+#ifndef DRIVERS_PCI_PCI_C
+#define DRIVERS_PCI_PCI_C
+
+typedef void (*pci_func_t)(uint32_t device, uint16_t vendor_id, uint16_t device_id, void * extra);
+void pci_scan_bus(pci_func_t f, int type, int bus, void * extra);
+
+#define PCI_VENDOR_ID            0x00 // 2
+#define PCI_DEVICE_ID            0x02 // 2
+#define PCI_COMMAND              0x04 // 2
+#define PCI_STATUS               0x06 // 2
+#define PCI_REVISION_ID          0x08 // 1
+
+#define PCI_PROG_IF              0x09 // 1
+#define PCI_SUBCLASS             0x0a // 1
+#define PCI_CLASS                0x0b // 1
+#define PCI_CACHE_LINE_SIZE      0x0c // 1
+#define PCI_LATENCY_TIMER        0x0d // 1
+#define PCI_HEADER_TYPE          0x0e // 1
+#define PCI_BIST                 0x0f // 1
+#define PCI_BAR0                 0x10 // 4
+#define PCI_BAR1                 0x14 // 4
+#define PCI_BAR2                 0x18 // 4
+#define PCI_BAR3                 0x1C // 4
+#define PCI_BAR4                 0x20 // 4
+#define PCI_BAR5                 0x24 // 4
+
+#define PCI_INTERRUPT_LINE       0x3C // 1
+
+#define PCI_SECONDARY_BUS        0x19 // 1
+
+#define PCI_HEADER_TYPE_DEVICE  0
+#define PCI_HEADER_TYPE_BRIDGE  1
+#define PCI_HEADER_TYPE_CARDBUS 2
+
+#define PCI_TYPE_BRIDGE 0x0604
+#define PCI_TYPE_SATA   0x0106
+
+#define PCI_ADDRESS_PORT 0xCF8
+#define PCI_VALUE_PORT   0xCFC
+
+#define PCI_NONE 0xFFFF
+
+typedef void (*pci_func_t)(uint32_t device, uint16_t vendor_id, uint16_t device_id, void * extra);
+
+static inline int pci_extract_bus(uint32_t device) {
+	return (uint8_t)((device >> 16));
+}
+static inline int pci_extract_slot(uint32_t device) {
+	return (uint8_t)((device >> 8));
+}
+static inline int pci_extract_func(uint32_t device) {
+	return (uint8_t)(device);
+}
+
+static inline uint32_t pci_get_addr(uint32_t device, int field) {
+	return 0x80000000 | (pci_extract_bus(device) << 16) | (pci_extract_slot(device) << 11) | (pci_extract_func(device) << 8) | ((field) & 0xFC);
+}
+
+static inline uint32_t pci_box_device(int bus, int slot, int func) {
+	return (uint32_t)((bus << 16) | (slot << 8) | func);
+}
+
+
+void pci_write_field(uint32_t device, int field, int size, uint32_t value) {
+	outl(PCI_ADDRESS_PORT, pci_get_addr(device, field));
+	outl(PCI_VALUE_PORT, value);
+}
+
+uint32_t pci_read_field(uint32_t device, int field, int size) {
+	outl(PCI_ADDRESS_PORT, pci_get_addr(device, field));
+
+	if (size == 4) {
+		uint32_t t = inl(PCI_VALUE_PORT);
+		return t;
+	} else if (size == 2) {
+		uint16_t t = inw(PCI_VALUE_PORT + (field & 2));
+		return t;
+	} else if (size == 1) {
+		uint8_t t = inb(PCI_VALUE_PORT + (field & 3));
+		return t;
+	}
+	return 0xFFFF;
+}
+
+uint16_t pci_find_type(uint32_t dev) {
+	return (pci_read_field(dev, PCI_CLASS, 1) << 8) | pci_read_field(dev, PCI_SUBCLASS, 1);
+}
+
+
+void pci_scan_hit(pci_func_t f, uint32_t dev, void * extra) {
+	int dev_vend = (int)pci_read_field(dev, PCI_VENDOR_ID, 2);
+	int dev_dvid = (int)pci_read_field(dev, PCI_DEVICE_ID, 2);
+
+	f(dev, dev_vend, dev_dvid, extra);
+}
+
+void pci_scan_func(pci_func_t f, int type, int bus, int slot, int func, void * extra) {
+	uint32_t dev = pci_box_device(bus, slot, func);
+	if (type == -1 || type == pci_find_type(dev)) {
+		pci_scan_hit(f, dev, extra);
+	}
+	if (pci_find_type(dev) == PCI_TYPE_BRIDGE) {
+		pci_scan_bus(f, type, pci_read_field(dev, PCI_SECONDARY_BUS, 1), extra);
+	}
+}
+
+void pci_scan_slot(pci_func_t f, int type, int bus, int slot, void * extra) {
+	uint32_t dev = pci_box_device(bus, slot, 0);
+	if (pci_read_field(dev, PCI_VENDOR_ID, 2) == PCI_NONE) {
+		return;
+	}
+	pci_scan_func(f, type, bus, slot, 0, extra);
+	if (!pci_read_field(dev, PCI_HEADER_TYPE, 1)) {
+		return;
+	}
+	for (int func = 1; func < 8; func++) {
+		uint32_t dev = pci_box_device(bus, slot, func);
+		if (pci_read_field(dev, PCI_VENDOR_ID, 2) != PCI_NONE) {
+			pci_scan_func(f, type, bus, slot, func, extra);
+		}
+	}
+}
+
+void pci_scan_bus(pci_func_t f, int type, int bus, void * extra) {
+	for (int slot = 0; slot < 32; ++slot) {
+		pci_scan_slot(f, type, bus, slot, extra);
+	}
+}
+
+void pci_scan(pci_func_t f, int type, void * extra) {
+
+	if ((pci_read_field(0, PCI_HEADER_TYPE, 1) & 0x80) == 0) {
+		pci_scan_bus(f,type,0,extra);
+		return;
+	}
+
+	for (int func = 0; func < 8; ++func) {
+		uint32_t dev = pci_box_device(0, 0, func);
+		if (pci_read_field(dev, PCI_VENDOR_ID, 2) != PCI_NONE) {
+			pci_scan_bus(f, type, func, extra);
+		} else {
+			break;
+		}
+	}
+}
+
+static void find_isa_bridge(uint32_t device, uint16_t vendorid, uint16_t deviceid, void * extra) {
+	if (vendorid == 0x8086 && (deviceid == 0x7000 || deviceid == 0x7110)) {
+		*((uint32_t *)extra) = device;
+	}
+}
+static uint32_t pci_isa = 0;
+static uint8_t pci_remaps[4] = {0};
+void pci_remap(void) {
+	pci_scan(&find_isa_bridge, -1, &pci_isa);
+	if (pci_isa) {
+		for (int i = 0; i < 4; ++i) {
+			pci_remaps[i] = pci_read_field(pci_isa, 0x60+i, 1);
+			if (pci_remaps[i] == 0x80) {
+				pci_remaps[i] = 10 + (i%1);
+			}
+		}
+		uint32_t out = 0;
+		memcpy(&out, &pci_remaps, 4);
+		pci_write_field(pci_isa, 0x60, 4, out);
+	}
+}
+
+int pci_get_interrupt(uint32_t device) {
+
+	if (pci_isa) {
+		uint32_t irq_pin = pci_read_field(device, 0x3D, 1);
+		if (irq_pin == 0) {
+			return pci_read_field(device, PCI_INTERRUPT_LINE, 1);
+		}
+		int pirq = (irq_pin + pci_extract_slot(device) - 2) % 4;
+		int int_line = pci_read_field(device, PCI_INTERRUPT_LINE, 1);
+		if (pci_remaps[pirq] >= 0x80) {
+			if (int_line == 0xFF) {
+				int_line = 10;
+				pci_write_field(device, PCI_INTERRUPT_LINE, 1, int_line);
+			}
+			pci_remaps[pirq] = int_line;
+			uint32_t out = 0;
+			memcpy(&out, &pci_remaps, 4);
+			pci_write_field(pci_isa, 0x60, 4, out);
+			return int_line;
+		}
+		pci_write_field(device, PCI_INTERRUPT_LINE, 1, pci_remaps[pirq]);
+		return pci_remaps[pirq];
+	} else {
+		return pci_read_field(device, PCI_INTERRUPT_LINE, 1);
+	}
+}
+
+#endif // DRIVERS_PCI_PCI_C

kernel/inline_asm.c

@@ -31,13 +31,33 @@ static inline uint8_t inb(uint16_t port) {
     return ret;
 }
 
+static uint16_t inw(uint16_t port) {
+	uint16_t ret;
+	asm volatile ("inw %1, %0" : "=a" (ret) : "dN" (port));
+	return ret;
+}
+
+static void outw(uint16_t port, uint16_t val) {
+	asm volatile ("outw %0, %1" : : "a" (val), "dN" (port) );
+}
+
+static uint32_t inl(uint16_t port) {
+	uint32_t ret;
+	asm volatile ("inl %%dx, %%eax" : "=a" (ret) : "dN" (port));
+	return ret;
+}
+
+static void outl(uint16_t port, uint32_t val) {
+	asm volatile ("outl %%eax, %%dx" : : "dN" (port), "a" (val));
+}
+
 static inline void lidt(void* base, uint16_t size)
 {   // This function works in 32 and 64bit mode
     struct {
         uint16_t length;
         void*    base;
     } __attribute__((packed)) IDTR = { size, base };
- 
+
     asm ( "lidt %0" : : "m"(IDTR) );  // let the compiler choose an addressing mode
 }
 
@@ -61,4 +81,20 @@ static inline void sgdt(gdt_desc* ret) {
     asm volatile ("sgdt %0" : : "m"(*ret) : "memory");
 }
 
-#endif //INLINE ASM_C
+static void * memcpy(void * restrict dest, const void * restrict src, long n) {
+	asm volatile("cld; rep movsb"
+	            : "=c"((int){0})
+	            : "D"(dest), "S"(src), "c"(n)
+	            : "flags", "memory");
+	return dest;
+}
+
+static void * memset(void * dest, int c, long n) {
+	asm volatile("cld; rep stosb"
+	             : "=c"((int){0})
+	             : "D"(dest), "a"(c), "c"(n)
+	             : "flags", "memory");
+	return dest;
+}
+
+#endif //INLINE ASM_C

kernel/interrupts.c

@@ -32,12 +32,12 @@ void interrupt_new_handler(int intnum, void (*handler)(interrupt_frame*)) {
 
 void interrupt_init() {
     /* ICW1 - begin initialization */
-	outb(0x20, 0x11);
+    outb(0x20, 0x11);
     outb(0xA0, 0x11);
 
     /* ICW2 - remap offset address of IDT */
     outb(0x21, 0x20);
-    outb(0xA1, 0x82);
+    outb(0xA1, 0x28);
 
     /* ICW3 - setup cascading */
     outb(0x21, 0x00);
@@ -47,9 +47,9 @@ void interrupt_init() {
     outb(0x21, 0x01);
     outb(0xA1, 0x01);
 
-	/* mask interrupts */
-	outb(0x21 , 0xff);
-	outb(0xA1 , 0xff);
+    /* mask interrupts */
+    outb(0x21 , 0xff);
+    outb(0xA1 , 0xff);
 
     // Exceptions
     interrupt_new_handler(DIVIDE_BY_ZERO,           divide_by_zero_handler);
@@ -89,9 +89,10 @@ void interrupt_init() {
 
     uint16_t size = (sizeof(idt_entry) * 256);
 
-	lidt(IDT, size);
+    lidt(IDT, size);
 
     keyboard_init();
+
 }
 
-#endif //INTERRUPTS_C
+#endif //INTERRUPTS_C

kernel/kernel.c

@@ -2,7 +2,7 @@
 #if defined(__linux__)
 #error "You are not using a cross-compiler, you will most certainly run into trouble"
 #endif
- 
+
 /* This tutorial will only work for the 32-bit ix86 targets. */
 #if !defined(__i386__)
 #error "This kernel needs to be compiled with a ix86-elf compiler"
@@ -16,6 +16,7 @@
 #include "memory.c"
 #include "interrupts.c"
 #include "shell.c"
+#include "network.c"
 
 static inline bool are_interrupts_enabled() {
     unsigned long flags;
@@ -25,7 +26,7 @@ static inline bool are_interrupts_enabled() {
     return flags & (1 << 9);
 }
 
-void kernel_main(void) 
+void kernel_main(void)
 {
 	/* Initialize terminal interface */
 	terminal_initialize();
@@ -35,11 +36,11 @@ void kernel_main(void)
 	terminal_putchar('l');
 	terminal_putchar('l');
 	terminal_putchar('o');
- 
-    terminal_setcolor(vga_entry_color(VGA_COLOR_GREEN, VGA_COLOR_BLACK));
-    terminal_writestring(" kernel");
-    terminal_setcolor(vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK));
-    terminal_writestring(" World!\n");
+
+  terminal_setcolor(vga_entry_color(VGA_COLOR_GREEN, VGA_COLOR_BLACK));
+  terminal_writestring(" kernel");
+  terminal_setcolor(vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK));
+  terminal_writestring(" World!\n");
 	terminal_writestring("Newlines!\n");
 
 	char* memory_str = alloc(sizeof(char) * 7);
@@ -60,8 +61,9 @@ void kernel_main(void)
 	terminal_writestring((are_interrupts_enabled())? "Interrupts!\n": "No interrupts :(\n");
 
 	interrupt_init();
+  network_init();
 
 	for(;;) {
 		shell_step();
 	}
-}
+}

kernel/network.c

@@ -0,0 +1 @@
+#include "drivers/networking/network.c"

kernel/util/ringbuffer.c

@@ -0,0 +1,111 @@
+#ifndef RINGBUFFER_C
+#define RINGBUFFER_C
+
+#include "ringbuffer.h"
+#include "../memory.c"
+
+#define ERROR(msg) \
+	do { \
+		/* TODO Do something error-ish */ \
+	} while(0)
+
+#define ASSERT_NONNULL_ARG(argument) { \
+	if (argument == NULL) { \
+		ERROR(__func__ " got NULL for argument '" #argument "'"); \
+	} \
+}
+
+
+struct ringbuffer* rbfr_create(const int capacity, void (*const destroy_element)(void*)) {
+	ASSERT_NONNULL_ARG(destroy_element);
+
+	struct ringbuffer* const this = alloc(sizeof (struct ringbuffer));
+
+	this->buffer = alloc(capacity * sizeof (void*));
+	this->buffer_n = capacity;
+	this->size = 0;
+	this->head = 0;
+
+	this->destroy_element = destroy_element;
+
+	return this;
+}
+
+void rbfr_destroy(struct ringbuffer* const this) {
+	ASSERT_NONNULL_ARG(this);
+
+	rbfr_clear(this);
+
+	free(this->buffer);
+	this->buffer = NULL;
+
+	free(this);
+}
+
+int rbfr_size(const struct ringbuffer* const this) {
+	ASSERT_NONNULL_ARG(this);
+
+	return this->size;
+}
+
+int rbfr_capacity(const struct ringbuffer* this) {
+	ASSERT_NONNULL_ARG(this);
+	return this->buffer_n;
+}
+
+void rbfr_enqueue(struct ringbuffer* this, void* const element) {
+	ASSERT_NONNULL_ARG(this);
+
+	if (this->buffer_n == 0) {
+		return;
+	}
+
+	int index = this->head + this->size;
+	if (index >= this->buffer_n) {
+		index -= this->buffer_n;
+	}
+	this->buffer[index] = element;
+	if (this->size < this->buffer_n) {
+		this->size++;
+	} else {
+		this->head++;
+	}
+	return;
+}
+
+bool rbfr_peek(const struct ringbuffer *const this, void** element) {
+	ASSERT_NONNULL_ARG(this);
+	ASSERT_NONNULL_ARG(element);
+
+	if (this->size == 0) {
+		return false;
+	}
+	*element = this->buffer[this->head];
+	return true;
+}
+
+bool rbfr_dequeue(struct ringbuffer *const this, void** element) {
+	ASSERT_NONNULL_ARG(this);
+	ASSERT_NONNULL_ARG(element);
+
+	if (!rbfr_peek(this, element)) {
+		return false;
+	}
+	this->size--;
+	this->head++;
+	if (this->head >= this->buffer_n) {
+		this->head = 0;
+	}
+	return true;
+}
+
+void rbfr_clear(struct ringbuffer* this) {
+	ASSERT_NONNULL_ARG(this);
+
+	void* element;
+	while (rbfr_dequeue(this, &element)) {
+		this->destroy_element(element);
+	}
+}
+
+#endif // RINGBUFFER_C

kernel/util/ringbuffer.h

@@ -0,0 +1,80 @@
+#ifndef RINGBUFFER_H
+#define RINGBUFFER_H
+
+#include <stdbool.h>
+
+// Data layout:                ↓head
+// buffer = [ 4, undef, undef, 1, 2, 3 ]
+// where 1 is the oldest element and 4 the newest.
+// Enqueue adds the element after 4 and dequeue removes 1.
+struct ringbuffer {
+	int head;
+	int size;
+	void (*destroy_element)(void*);
+	int buffer_n;
+	void** buffer;
+};
+
+/**
+ * Allocate memory and initialize a circular queue with given capacity
+ *
+ * A ringbuffer, or circular queue, is like a regular queue, but if it's full when you add an
+ * element, it displaces the oldest element to make place. As such, adding elements never fails.
+ *
+ * Memory: this function allocates memory for the queue (free it with rbfr_destroy). The
+ * destroy_element function user has to provide must free an element's memory.
+ *
+ * @param  capacity         maximum amount of elements to accept without dropping oldest
+ * @param  destroy_element  function called when the queue has to drop an element, with the element
+ *                          passed as argument
+ * @return pointer to ringbuffer
+ */
+struct ringbuffer* rbfr_create(const int capacity, void (*destroy_element)(void*));
+
+/**
+ * Free the queue's memory
+ *
+ * Memory: all elements still present are freed using the destroy_element function provided by user
+ * in rbfr_create.
+ */
+void rbfr_destroy(struct ringbuffer* this);
+
+int rbfr_size(const struct ringbuffer* this);
+
+int rbfr_capacity(const struct ringbuffer* this);
+
+/**
+ * Add one element at the end
+ *
+ * If the queue is full (if size==capacity), the oldest element is removed to make place. As such,
+ * this operation does not fail if the queue is full.
+ *
+ * Memory: if an element has to be removed to make place, it is freed using the destroy_element
+ * function provided by user in rbfr_create.
+ */
+void rbfr_enqueue(struct ringbuffer* this, void* element);
+
+/**
+ * Return first element without removing it from the buffer
+ *
+ * Memory: do not free the element's memory, it still lives in the ringbuffer.
+ */
+bool rbfr_peek(const struct ringbuffer* this, void** element);
+
+/**
+ * Remove first element and return it
+ *
+ * Memory: user is responsible for freeing the element's memory.
+ */
+bool rbfr_dequeue(struct ringbuffer* this, void** element);
+
+/**
+ * Remove all elements
+ *
+ * Memory: this function destroys elements using the destroy_element function provided by user in
+ * rbfr_create.
+ */
+void rbfr_clear(struct ringbuffer* this);
+
+
+#endif // RINGBUFFER_H