145 lines
2.7 KiB
C
145 lines
2.7 KiB
C
#include <stdlib.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <stdarg.h>
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#include <errno.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include "x86emu.h"
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static uint8_t ram[1025*1024];
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static int floppy_fd;
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static X86EMU_intrFuncs intr_funcs[256];
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void printk(const char* format, ...)
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{
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va_list ap;
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va_start(ap, format);
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vfprintf(stderr, format, ap);
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va_end(ap);
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}
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static void unknown_interrupt_cb(int num)
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{
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printk("unknown interrupt 0x%02x\n", num);
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exit(1);
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}
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static void ignored_interrupt_cb(int num)
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{
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M.x86.R_AX = 0;
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}
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static void int10_cb(int num)
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{
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switch (M.x86.R_AH)
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{
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case 0x0e: /* print char al */
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putchar(M.x86.R_AL);
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fflush(stdout);
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break;
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default:
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printk("unknown int10 service 0x%02x\n", M.x86.R_AH);
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exit(1);
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}
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}
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static void int13_cb(int num)
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{
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if (M.x86.R_DL != 0)
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{
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/* unknown disk */
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M.x86.R_AX = 1;
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return;
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}
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switch (M.x86.R_AH)
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{
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case 0x02: /* read sector */
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{
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/* On entry:
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* al: number of sectors
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* bx: address
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* ch: track
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* cl: sector
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* dh: head number
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* dl: disk
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*/
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uint8_t count = M.x86.R_AL;
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uint32_t address = (M.x86.R_DS << 4) + M.x86.R_BX;
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uint8_t sector = M.x86.R_CL;
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uint8_t track = M.x86.R_CH;
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uint8_t head = M.x86.R_DH;
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uint32_t lba = track*18*2 + head*18 + (sector-1);
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//printf("CHS %d.%d.%d -> lba 0x%x\n", track, head, sector, lba);
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pread(floppy_fd, &ram[address], count*512, lba*512);
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M.x86.R_AX = 0;
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CLEAR_FLAG(F_CF);
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}
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case 0x08: /* probe disk al */
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M.x86.R_AX = 0;
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M.x86.R_CL = 18; /* maximum sector number */
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M.x86.R_DH = 1; /* maximum head number */
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/* there's other stuff we should set as well */
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break;
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default:
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printk("unknown int13 service 0x%02x\n", M.x86.R_AH);
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exit(1);
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}
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}
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int main(int argc, const char* argv[])
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{
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if (argc != 2)
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{
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printk("syntax: pc86emu <fdimage.img>\n");
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exit(1);
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}
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floppy_fd = open(argv[1], O_RDONLY);
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if (floppy_fd == -1)
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{
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printk("could not open disk image: %s\n", strerror(errno));
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exit(1);
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}
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/* Initialise the processor. */
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M.mem_base = (uintptr_t) ram;
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M.mem_size = sizeof(ram);
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/* Load the boot sector at 0x07c0:0000. */
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for (int i=0; i<512; i++)
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{
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uint8_t b;
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read(floppy_fd, &b, 1);
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wrb(0x7c00 + i, b);
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}
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/* Initialise. */
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for (int i=0; i<256; i++)
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intr_funcs[i] = unknown_interrupt_cb;
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intr_funcs[0x10] = int10_cb;
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intr_funcs[0x13] = int13_cb;
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intr_funcs[0x14] = ignored_interrupt_cb; /* serial port stuff */
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//M.x86.debug = DEBUG_TRACE_F|DEBUG_STEP_F|DEBUG_DECODE_F;
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M.x86.debug = 0;
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M.x86.R_CS = 0x07c0;
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M.x86.R_IP = 0x0000;
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M.x86.R_DL = 0; /* boot drive */
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X86EMU_setupIntrFuncs(intr_funcs);
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X86EMU_exec();
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return 0;
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}
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