ref: bdd385803dcbccdf2750f7259a1784744541dec4
dir: /sys/src/boot/pc/l.s/
#include "x16.h" #include "mem.h" #undef ORB #define DATA32SEL SELECTOR(1, SELGDT, 0) #define EXEC32SEL SELECTOR(2, SELGDT, 0) #define DATA16SEL SELECTOR(3, SELGDT, 0) #define EXEC16SEL SELECTOR(4, SELGDT, 0) #define SEGSS BYTE $0x36 #define SEGES BYTE $0x26 #define FARRET BYTE $0xCB TEXT origin(SB), $0 CLI CLR(rCX) MTSR(rCX, rSS) OPSIZE; MOVL $origin(SB), SP PUSHA OPSIZE; ADSIZE; PUSHL SP OPSIZE; ADSIZE; PUSHL CX PUSHI(start(SB)) TEXT pmode32(SB), $0 CLI /* get return pc */ POPR(rDI) /* make sure stack is at 0000: */ CLR(rCX) MTSR(rCX, rSS) OPSIZE; ANDL $0xFFFF, SP /* convert 16-bit return pc to far pointer */ PUSHI(EXEC32SEL) PUSHR(rDI) /* load gdt */ SEGSS; LGDT(tgdtptr(SB)) /* enable protected mode */ MFCR(rCR0, rCX) ORB $1, CL MTCR(rCX, rCR0) /* flush */ FARJUMP16(EXEC16SEL, pmode32flush(SB)); TEXT pmode32flush(SB), $0 /* load 32-bit protected mode data selector */ LWI(DATA32SEL, rCX) _segret: /* load all data segments */ MTSR(rCX, rDS) MTSR(rCX, rES) MTSR(rCX, rFS) MTSR(rCX, rGS) MTSR(rCX, rSS) FARRET TEXT rmode16(SB), $0 /* setup farret to rmode16x */ PUSHL $EXEC16SEL PUSHL $rmode16x(SB) /* load 16-bit protected mode data selector */ MOVL $DATA16SEL, CX JMP _segret TEXT rmode16x(SB), $0 /* disable protected mode */ MFCR(rCR0, rCX) ANDB $0xfe, CL MTCR(rCX, rCR0) /* flush */ FARJUMP16(0, rmode16flush(SB)); TEXT rmode16flush(SB), $0 /* * load 16-bit realmode data segment 0000: and * return to 32 bit return pc interpreted * as 16 bit far pointer. */ CLR(rCX) JMP _segret TEXT tgdt(SB), $0 /* null descriptor */ LONG $0 LONG $0 /* data segment descriptor for 4 gigabytes (PL 0) */ LONG $(0xFFFF) LONG $(SEGG|SEGB|(0xF<<16)|SEGP|SEGPL(0)|SEGDATA|SEGW) /* exec segment descriptor for 4 gigabytes (PL 0) */ LONG $(0xFFFF) LONG $(SEGG|SEGD|(0xF<<16)|SEGP|SEGPL(0)|SEGEXEC|SEGR) /* data segment descriptor for (PL 0) 16-bit */ LONG $(0xFFFF) LONG $((0xF<<16)|SEGP|SEGPL(0)|SEGDATA|SEGW) /* exec segment descriptor for (PL 0) 16-bit */ LONG $(0xFFFF) LONG $((0xF<<16)|SEGP|SEGPL(0)|SEGEXEC|SEGR) TEXT tgdtptr(SB), $0 WORD $(5*8) LONG $tgdt(SB) TEXT jump(SB), $0 MOVL 4(SP), AX JMP *AX TEXT halt(SB), $0 _halt: JMP _halt TEXT kbdgetc(SB), $0 CALL rmode16(SB) STI MOVB $0x01, AH BIOSCALL(0x16) JNZ _gotkey CLR(rAX) JMP _pret32 _gotkey: CLR(rAX) BIOSCALL(0x16) JMP _pret32 TEXT cgaputc(SB), $0 MOVL 4(SP),AX CALL rmode16(SB) STI MOVB $0x0E, AH BIOSCALL(0x10) _pret32: CALL16(pmode32(SB)) ANDL $0xFFFF, AX RET TEXT usleep(SB), $0 MOVL t+4(SP), AX PUSHL AX CALL rmode16(SB) STI POPR(rDX) POPR(rCX) MOVB $0x86, AH BIOSCALL(0x15) JMP _pret32 #ifdef PXE TEXT pxeinit(SB), $0 CALL rmode16(SB) /* get pxe env structure in ES:BX */ LWI(0x5650, rAX) BIOSCALL(0x1A) JC _pret32 /* !PXE or PXEENV+ signature */ SEGES; LXW(0, xBX, rAX) CMPI((('!'<<0)|('P'<<8)), rAX) JEQ _getentry CMPI((('P'<<0)|('X'<<8)), rAX) JNE _pret32 SEGES; LXW(0x2A, xBX, rAX) SEGES; LXW(0x28, xBX, rBX) MTSR(rAX, rES) _getentry: SEGES; LXW(0x12, xBX, rAX) SW(rAX, pxepseg(SB)) SEGES; LXW(0x10, xBX, rAX) SW(rAX, pxepoff(SB)) CLR(rAX) JMP _pret32 TEXT pxecallret(SB), $0 ADDI(6, rSP) JMP _pret32 TEXT pxecall(SB), $0 MOVL op+4(SP),AX MOVL buf+8(SP),SI CALL rmode16(SB) CLR(rCX) PUSHR(rCX) PUSHR(rSI) /* opcode */ PUSHR(rAX) /* farcall */ PUSHR(rCX) PUSHI(pxecallret(SB)) LW(pxepseg(SB), rAX) PUSHR(rAX) LW(pxepoff(SB), rAX) PUSHR(rAX) STI CLR(rAX) CLR(rBX) CLR(rCX) CLR(rDX) CLR(rDI) CLR(rSI) FARRET TEXT pxepseg(SB), $0 WORD $0 TEXT pxepoff(SB), $0 WORD $0 #else /* PXE */ /* * in: * DL drive * AX:BX lba32, * 0000:SI buffer */ TEXT readsect16(SB), $0 PUSHA CLR(rCX) PUSHR(rCX) /* qword lba */ PUSHR(rCX) PUSHR(rBX) PUSHR(rAX) PUSHR(rCX) /* dword buffer */ PUSHR(rSI) INC(rCX) PUSHR(rCX) /* word # of sectors */ PUSHI(0x0010) /* byte reserved, byte packet size */ MW(rSP, rSI) LWI(0x4200, rAX) BIOSCALL(0x13) JCC _readok ADDI(0x10, rSP) POPA CLR(rAX) DEC(rAX) RET _readok: ADDI(0x10, rSP) POPA CLR(rAX) RET TEXT readsect(SB), $0 MOVL 4(SP), DX MOVW 8(SP), AX MOVW 10(SP), BX MOVL 12(SP), SI CALL rmode16(SB) STI CALL16(readsect16(SB)) CALL16(pmode32(SB)) ANDL $0xFFFF, AX RET #endif #ifdef ISO TEXT bootname(SB), $0 BYTE $'3'; BYTE $'8'; BYTE $'6'; BYTE $'/'; BYTE $'9'; BYTE $'b'; BYTE $'o'; BYTE $'o'; BYTE $'t'; BYTE $'i'; BYTE $'s'; BYTE $'o'; BYTE $0 #endif TEXT uart(SB), $0 BYTE $0xff TEXT nocga(SB), $0 BYTE $0x00 TEXT nokbd(SB), $0 BYTE $0x00 TEXT hex(SB), $0 BYTE $'0'; BYTE $'1'; BYTE $'2'; BYTE $'3'; BYTE $'4'; BYTE $'5'; BYTE $'6'; BYTE $'7'; BYTE $'8'; BYTE $'9'; BYTE $'a'; BYTE $'b'; BYTE $'c'; BYTE $'d'; BYTE $'e'; BYTE $'f'