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64 lines
2.3 KiB
C++
64 lines
2.3 KiB
C++
#include "pic.h"
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#include "ioport.h"
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namespace PIC {
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void initialize() {
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// Access primary & secondary PIC via two ports each
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IOPort primary_port_a(0x20);
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IOPort primary_port_b(0x21);
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IOPort secondary_port_a(0xa0);
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IOPort secondary_port_b(0xa1);
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// Initialization Command Word 1 (ICW1)
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// Basic PIC configuration, starting initialization
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enum InitializationCommandWord1 {
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ICW4_NEEDED = 1 << 0, // use Initialization Command Word 4
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SINGLE_MODE = 1 << 1, // Single or multiple (cascade mode) 8259A
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ADDRESS_INTERVAL_HALF =
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1 << 2, // 4 or 8 bit interval between the interrupt vector locations
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LEVEL_TRIGGERED = 1 << 3, // Level or edge triggered
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ALWAYS_1 = 1 << 4,
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};
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const uint8_t icw1 = InitializationCommandWord1::ICW4_NEEDED |
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InitializationCommandWord1::ALWAYS_1;
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// ICW1 in port A (each)
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primary_port_a.outb(icw1);
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secondary_port_a.outb(icw1);
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// Initialization Command Word 2 (ICW2):
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// Configure interrupt vector base offset in port B
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primary_port_b.outb(0x20); // Primary: IRQ Offset 32
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secondary_port_b.outb(0x28); // Secondary: IRQ Offset 40
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// Initialization Command Word 3 (ICW3):
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// Configure pin on primary PIC connected to secondary PIC
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const uint8_t pin = 2; // Secondary connected on primary pin 2
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primary_port_b.outb(1 << pin); // Pin as bit mask for primary
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secondary_port_b.outb(pin); // Pin as value (ID) for secondary
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// Initialization Command Word 4 (ICW4)
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// Basic PIC configuration, starting initialization
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enum InitializationCommandWord4 {
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MODE_8086 = 1 << 0, // 8086/8088 or 8085 mode
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AUTO_EOI = 1 << 1, // Single or multiple (cascade mode) 8259A
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BUFFER_PRIMARY = 1 << 2, // Primary or secondary buffering
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BUFFERED_MODE =
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1 << 3, // Enable or disable buffering (for primary or secondary above)
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SPECIAL_FULLY_NESTED = 1 << 4 // Special or non special fully nested
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};
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const uint8_t icw4 = InitializationCommandWord4::MODE_8086 |
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InitializationCommandWord4::AUTO_EOI;
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// ICW3 in port B (each)
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primary_port_b.outb(icw4);
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secondary_port_b.outb(icw4);
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// Operation Control Word 1 (OCW1):
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// Disable (mask) all hardware interrupts on both legacy PICs (we'll use APIC)
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secondary_port_b.outb(0xff);
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primary_port_b.outb(0xff);
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}
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} // namespace PIC
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