39 lines
552 B
C
39 lines
552 B
C
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#include <stdint.h>
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#define COM1_BASE_PORT 0x3F8
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static inline uint8_t
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inb(uint16_t port)
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{
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uint8_t data;
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__asm__ ("inb %%dx, %%al" : "=a"(data) : "d"(port));
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return data;
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}
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static inline void
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outb(uint16_t port, uint8_t data)
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{
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__asm__ ("outb %%al, %%dx" :: "a"(data), "d"(port));
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}
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void serial_write_char(char c)
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{
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while (1) {
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int line_status = inb(COM1_BASE_PORT + 5);
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if (line_status & 0x20) {
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break;
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}
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}
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outb(COM1_BASE_PORT, c);
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}
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void
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main()
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{
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outb(0xE9, 'X');
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serial_write_char('X');
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for (;;) {
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__asm__ ("hlt" :);
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}
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}
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