137 lines
1.8 KiB
NASM
137 lines
1.8 KiB
NASM
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ORG BDOS
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%include "bios/header.asm"
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DISKBUF: EQU (BDOS-0x200) ; deblocking
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STACK: EQU (DISKBUF) ; grows down
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DEFDRV: EQU 4
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FCB_DRV: EQU 0 ; BYTE 0=A: 1=B: 2=C: ...
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FCB_NAM: EQU 1 ; 8 BYTES, space padded
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FCB_EXT: EQU 9 ; 3 BYTES, space padded
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FCB_TYP: EQU 12 ; 1 for regular file
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FCB_BLK: EQU 13 ; current 128b block in sector
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FCB_CLU: EQU 14 ; current sector
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FCB_LFT: EQU 16 ; bytes left to read in current file
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SYSCALL:
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TEST CL, CL
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JE SETUP
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CMP CL, 1
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JE GETC
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CMP CL, 2
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JE PUTC
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CMP CL, 9
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JE PUTS
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CMP CL, 10
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JE GETS
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STC
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RET
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SETUP:
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MOV SP, STACK
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MOV BYTE [DEFDRV], 0x01
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MOV CX, DISKBUF
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CALL SETDMA
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MOV DL, BYTE [DEFDRV]
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ADD DL, '@'
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CALL PUTC
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MOV DL, '>'
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CALL PUTC
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MOV DX, 0x7F
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MOV BYTE [0x7F], 0x2F
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MOV BYTE [0x80], 2
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CALL GETS
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INT3
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CLI
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HALT:
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HLT
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JMP HALT
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GETC:
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CALL CONIN
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TEST AL, AL
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JZ GETC
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PUSH DX
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MOV DL, AL
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CALL CONOUT
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POP DX
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ret
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PUTC:
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CALL CONOUT
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RET
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PUTS:
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PUSH SI
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MOV SI, DX
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PUTS_L:
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MOV DL, BYTE [SI]
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CMP DL, '$'
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JZ PUTS_E
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CALL CONOUT
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INC SI
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JMP PUTS_L
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PUTS_E:
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POP SI
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RET
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; BX base ptr to buffer
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; CH maximum BL
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; CL minimum BL
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GETS:
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PUSH AX
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PUSH CX
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PUSH DX
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PUSH BX
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; BX is base pointer
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MOV BX, DX
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; CL is maximum, CH is current position
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MOV CX, [BX]
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XOR CH, CH
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; BX starts at actual character area
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ADD BX, 2
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GETS_L:
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; Read and maybe handle control chars
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CALL GETC
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CMP AL, 0x0D
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JE GETS_E
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CMP AL, 8
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JE GETS_BS
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; Store character
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PUSH BX
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ADD BL, CH
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ADC BH, 0
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MOV [BX], AL
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POP BX
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; Loop if we arent full yet
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INC CH
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CMP CH, CL
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JC GETS_L
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GETS_E:
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; Append LF to CR
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MOV DL, 0x0A
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CALL PUTC
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; Write back length data
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SUB BX, 2
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MOV [BX], CX
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; Restore registers
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POP BX
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POP DX
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POP CX
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POP AX
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ret
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GETS_BS:
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TEST CH, CH
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JZ GETS_L
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MOV DL, 0x20
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CALL PUTC
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MOV DL, 8
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CALL PUTC
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DEC CL
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JMP GETS_L
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