/ Disassembly listing of eternal ramdisk program / default_device = 7 / Default device number (7=H:) default_size = 100 / Default ramdisk size (in units of 1K) magic = 0x200 / Used to detect restart / Absolute memory locations / reset_vector= 0x004 membot = 0x432 memtop = 0x436 phystop = 0x42E hdv_bpb = 0x472 hdv_rw = 0x476 hdv_mediach = 0x47E drivebits = 0x4C4 / DOS operation codes / Mshrink = 0x4A Super = 0x20 Fopen = 0x3D Fclose = 0x3E Fread = 0x3F /--------------------------------------------------------------- .shri movea.l a7, a5 / save old stack ptr movea.l $stack, a7 / new stack movea.l 4(a5), a5 / get address of base page move.l 12(a5), d0 / compute length of program add.l 20(a5), d0 add.l 28(a5), d0 add.l $0x100, d0 move.l d0, -(a7) / size move.l a5, -(a7) / mem move.w d0, -(a7) / zero move.w $Mshrink, -(a7) / return unused memory trap $1 / DOS adda.l $12, a7 / pop stack clr.l -(a7) / 0 move.w $Super, -(a7) / Super trap $1 / DOS addq.l $6, a7 / pop stack move.l d0, old_ssp / save old SSP movea.l $memtop, a4 movea.l $phystop, a5 movea.l (a5), a1 cmpi.w $magic, (a1) beq restart / read file "\auto\ramdisk.dat" move.w $0,-(a7) / open file move.l $filename,-(a7) move.w $Fopen,-(a7) trap $1 addq.l $8,a7 cmpi.w $0, d0 / check for error bmi L3 / branch if open failed move.w d0,d7 / save file handle move.l $buffer,-(a7) / read file move.l $3,-(a7) move.w d7,-(a7) move.w $Fread,-(a7) trap $1 adda.l $12,a7 cmpi.l $3,d0 bne.s L3 / make sure 3 bytes were read move.w d7,-(a7) / close file move.w $Fclose,-(a7) trap $1 addq.l $4,a7 clr.l d0 move.b buffer, d0 move.w d0, device_no / save for future use move.w d0, rd_mediach+2 / put device number in cmpi instr. move.w d0, rd_bpb+2 move.w d0, rd_rw+2 move.b buffer+1, d0 / get ramdisk size (in K-bytes) lsl.l $8,d0 move.b buffer+2, d0 bra.s L5 L3: move.l $default_size, d0 / file not found -- use default size L5: move.w d0, numcl / put number of clusters in bpb moveq.l $10, d2 lsl.l d2, d0 / d0 = ramd size in bytes add.l $[9216+512], d0 / leave space for boot sector / + FAT + root dir + BPB + driver move.l d0, d1 / make sure to leave at least 128K to user add.l membot, d1 add.l $0x20000, d1 cmp.l (a4), d1 bge.s exit sub.l d0, (a4) / okay, so reserve memory sub.l d0, (a5) move.l hdv_bpb, old_bpb+2 / save hdv_bpb vector move.l hdv_rw, old_rw+2 / save hdv_rw vector move.l hdv_mediach, old_mediach+2 / save hdv_mediach vector movea.l $driver, a0 / copy drivers to reserved memory movea.l (a5), a1 moveq.l $127, d7 / move 512 bytes L4: move.l (a0)+, (a1)+ dbf d7, L4 movea.l reset_vector, a0 / force a reset jmp (a0) restart: move.l (a5), d1 add.l $[rd_bpb - driver], d1 move.l d1, hdv_bpb / set hdv_bpb vector move.l (a5), d1 add.l $[rd_rw - driver], d1 move.l d1, hdv_rw / set hdv_rw vector move.l (a5), d1 add.l $[rd_mediach - driver], d1 move.l d1, hdv_mediach / set hdv_mediach vector movea.l (a5), a0 / mark ramdisk as present adda.l $[device_no - driver], a0 move.w (a0), d1 move.w drivebits, d0 bset d1, d0 move.w d0, drivebits exit: move.l old_ssp, -(a7) / leave supervisor mode move.w $Super, -(a7) trap $1 addq.l $6, a7 clr.w -(a7) / exit using Pterm0 trap $1 /---------------------------------------------------------- / Following bytes moved into high memory driver: / ramdisk bios parameter block recsiz: .word 512 / physical sector size in bytes clsiz: .word 2 / cluster size in sectors clsizb: .word 1024 / cluster size in bytes rdlen: .word 7 / root dir length in sectors fsiz: .word 5 / FAT size in sectors fatrec: .word 6 / sector # 2nd FAT start datrec: .word 18 / sector # data start numcl: .word 0x01EC / number of clusters (filled in above) bflags: .word 0 rd_mediach: cmpi $default_device, 4(a7) / mediach handler bne old_mediach moveq.l $0, d0 rts rd_bpb: cmpi $default_device, 4(a7) / bpb handler bne old_bpb move.l phystop, d0 rts rd_rw: cmpi $default_device, 14(a7) / rw handler bne old_rw movea.l phystop, a0 adda.l $512, a0 / start of ramdisk data area movea.l 6(a7), a1 / buffer address moveq.l $0, d1 move.w 12(a7), d1 / logical record number moveq.l $9, d0 / * 2^9 asl.l d0, d1 adda.l d1, a0 / + ramdisk base = sector address move.w 10(a7), d0 / sector count move.l a1, d2 / is buffer address odd? btst $0, d2 bne.s L8 / --yes, then branch btst $0, 5(a7) / check mode bne.s L6 / branch if write exg a1, a0 / read, so copy other way round L6: move.w $15, d1 / loop 16 times L7: move.l (a1)+, (a0)+ / move 32 bytes quickly move.l (a1)+, (a0)+ move.l (a1)+, (a0)+ move.l (a1)+, (a0)+ move.l (a1)+, (a0)+ move.l (a1)+, (a0)+ move.l (a1)+, (a0)+ move.l (a1)+, (a0)+ dbf d1, L7 subq.l $1, d0 / decrement count bne.s L6 / loop if more sectors to move rts L8: btst $0, 5(a7) / odd address buffer, so use slow move bne.s L9 / branch if write exg a1, a0 / read, so copy other way round L9: move.w $63, d1 / loop 64 times L10: move.b (a1)+, (a0)+ / move 8 bytes move.b (a1)+, (a0)+ move.b (a1)+, (a0)+ move.b (a1)+, (a0)+ move.b (a1)+, (a0)+ move.b (a1)+, (a0)+ move.b (a1)+, (a0)+ move.b (a1)+, (a0)+ dbf d1, L10 subq.l $1, d0 / decrement count bne.s L9 / loop if more sectors to move rts old_bpb: jmp 0 / vector to old bpb handler old_mediach: jmp 0 / vector to old mediach handler old_rw: jmp 0 / vector to old rw handler device_no: .word default_device / /----------------------- end of driver code ------------------------- .prvd filename: .ascii "\\auto\\ramdisk.dat\0" .bssd .even buffer: .=.+4 / character buffer old_ssp:.=.+0x4 / saved system stack pointer .=.+0x200 / stack stack: J9;fgHBİNu|/ BgHi