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robfinch |
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; ============================================================================
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; __
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; \\__/ o\ (C) 2013, 2014 Robert Finch, Stratford
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; \ __ / All rights reserved.
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; \/_// robfinch@opencores.org
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; ||
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;
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;
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; This source file is free software: you can redistribute it and/or modify
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; it under the terms of the GNU Lesser General Public License as published
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; by the Free Software Foundation, either version 3 of the License, or
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; (at your option) any later version.
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;
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; This source file is distributed in the hope that it will be useful,
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; but WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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; GNU General Public License for more details.
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;
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; You should have received a copy of the GNU General Public License
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; along with this program. If not, see .
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;
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; ============================================================================
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;
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MAX_VIRTUAL_PAGE EQU 320
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MAX_PHYSICAL_PAGE EQU 2048
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INV_PAGE EQU 000 ; page number to use for invalid entries
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;------------------------------------------------------------------------------
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; InitMMU
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;
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; Initialize the 64 maps of the MMU.
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; Initially all the maps are set the same:
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; Virtual Page Physical Page
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; 000-319 000 (invalid page marker)
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; 320-511 1856-2047
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; Note that there are only 512 virtual pages per map, and 2048 real
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; physical pages of memory. This limits maps to 32MB.
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; This range includes the BIOS assigned stacks for the tasks and tasks
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; virtual video buffers.
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; Note that physical pages 0 to 1855 are not mapped, but do exist. They may
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; be mapped into a task's address space as required.
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; If changing the maps the last 192 pages (12MB) of the map should always point
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; to the BIOS area. Don't change map entries 320-511 or the system may
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; crash. The last 192 pages map the virtual memory to the same physical
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; addresses so that the physical and virtual address are the same.
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; If the rts at the end of this routine works, then memory was mapped
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; successfully.
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;
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; System Memory Map (Physical Addresses)
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; Page
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; 0000 BASIC ROM, scratch memory ( 1 page global)
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; 0001-0063 unassigned (4MB - 63 pages)
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; 0064-0191 Bitmap video memory (8 MB - 128 pages)
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; 0192-0336 DOS usage, disk cache etc. (9.4MB - 145 pages)
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; 0337-1855 Heap space (99MB - 1519 pages)
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; 1856-1983 Virtual Screen buffers (8MB - 128 pages)
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; 1984-2047 BIOS/OS area (4MB - 64 pages)
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; 2032-2047 Stacks area (1MB - 16 pages)
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; 65535 BIOS ROM (64kB - 1 Page global)
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; 261952-262015 I/O area (4MB - 64 pages global)
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;------------------------------------------------------------------------------
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align 8
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public InitMMU:
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lda #1
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sta MMU_KVMMU+1
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dea
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sta MMU_KVMMU
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immu1:
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sta MMU_AKEY ; set access key for map
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ldx #0
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immu2:
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; set the first 320 pages to invalid page marker
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; set the last 192 pages to physical page 1856-2047
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ld r4,#INV_PAGE
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cpx #320
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blo immu3
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ld r4,r2
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add r4,r4,#1536 ; 1856-320
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immu3:
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st r4,MMU,x
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inx
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cpx #512
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bne immu2
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ina
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cmp #64 ; 64 MMU maps
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bne immu1
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stz MMU_OKEY ; set operating key to map #0
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lda #2
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sta MMU_FUSE ; set fuse to 2 clocks before mapping starts
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nop
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nop
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;------------------------------------------------------------------------------
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; Note that when switching the memory map, the stack address should not change
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; as the virtual address was mapped to the physical one.
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;------------------------------------------------------------------------------
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;
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align 8
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public EnableMMUMapping:
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pha
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lda RunningTCB ; no need to enable mapping for Monitor/Debugger job
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lda TCB_hJCB,r1
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cmp #2
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blo dmm2
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lda #12 ; is there even an MMU present ?
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bmt CONFIGREC
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beq emm1
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lda RunningTCB
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lda TCB_hJCB,r1
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sta MMU_OKEY ; select the mmu map for the job
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lda #2
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sta MMU_FUSE ; set fuse to 2 clocks before mapping starts
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lda #1
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sta MMU_MAPEN ; set MMU_MAPEN = 1
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emm1:
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pla
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rts
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public DisableMMUMapping:
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pha
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dmm2:
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lda #12 ; is there even an MMU present ?
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bmt CONFIGREC
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beq dmm1
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stz MMU_MAPEN
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dmm1:
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pla
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rts
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;------------------------------------------------------------------------------
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;------------------------------------------------------------------------------
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;
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SetAKEYForCurrentJob:
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pha
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jsr GetPtrCurrentJCB
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lda JCB_Map,r1
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sta MMU_AKEY
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pla
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rts
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;------------------------------------------------------------------------------
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;------------------------------------------------------------------------------
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;
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align 8
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public MemInit:
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lda #1 ; initialize memory semaphore
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sta mem_sema
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lda #1519
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sta nPagesFree
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; Initialize the allocated page map to zero.
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lda #64 ; 64*32 = 2048 bits
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ldx #0
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ldy #PageMap
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stos
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; Mark the last 192 pages as used (by the OS)
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; 6-32 bit words
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lda #-1
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sta PageMap+58
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sta PageMap+59
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sta PageMap+60
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sta PageMap+61
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sta PageMap+62
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sta PageMap+63
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; Mark page #0 used
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lda #1
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sta PageMap
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; Mark 64-336 used (DOS)
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lda #64
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meminit1:
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bms PageMap
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ina
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cmp #336
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blo meminit1
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rts
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;------------------------------------------------------------------------------
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; Allocate a memory page from the available memory pool.
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; Returns a pointer to the page in memory. The address returned is the
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; virtual memory address.
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;
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; Returns:
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; r1 = 0 if no more memory is available or max mapped capacity is reached.
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; r1 = virtual address of allocated memory page
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;------------------------------------------------------------------------------
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;
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align 8
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public AllocMemPage:
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phx
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phy
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; Search the page bitmap for a free memory page.
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lda #0
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ldx #MAX_PHYSICAL_PAGE
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spl mem_sema + 1
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amp2:
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bmt PageMap
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beq amp1 ; found a free page ?
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ina
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dex
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bne amp2
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; Here all memory pages are already in use. No more memmory is available.
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stz mem_sema + 1
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ply
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plx
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lda #0
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rts
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; Here we found an unallocated memory page. Next find a spot in the MMU
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; map to place the page.
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amp1:
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; Find unallocated map slot in the MMU
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jsr SetAKEYForCurrentJob
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ldx #0
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amp4:
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ldy MMU,x
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cpy #INV_PAGE
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beq amp3
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inx
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cpx #MAX_VIRTUAL_PAGE
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bne amp4
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; Here we searched the entire MMU slots and none were available
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stz mem_sema + 1
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ply
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plx
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lda #0 ; return NULL pointer
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rts
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; Here we have both an available page, and available map slot.
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amp3:
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bms PageMap ; mark page as allocated
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sta MMU,x ; put the page# into the map slot
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asl r1,r2,#14 ; pages are 16kW in size (compute virtual address)
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dec nPagesFree
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stz mem_sema + 1
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ply
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plx
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rts
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;------------------------------------------------------------------------------
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; Parameters:
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; r1 = size of allocation in words
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; Returns:
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; r1 = word pointer to memory
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; No MMU
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;------------------------------------------------------------------------------
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;
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align 8
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public AllocMemPages:
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php
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phx
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phy
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push r4
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sei
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amp5:
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tay
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lsr r3,r3,#14 ; convert amount to #pages
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iny ; round up
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cpy nPagesFree
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bhi amp11
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tyx ; x = request size in pages
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; Search for enough free pages to satisfy the request
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lda #0
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amp7:
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bmt PageMap ; test for a free page
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bne amp6 ; not a free page
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cpx #1 ; did we find enough free pages ?
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bls amp8
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dex
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amp6: ; keep checking for next free page
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ina
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cmp #1855 ; did we hit end of map ?
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bhi amp11 ; can't allocate enough memory
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bra amp7 ; go back and test for another free page
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; Insufficient memory, return NULL pointer
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amp11:
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lda #0
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pop r4
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ply
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plx
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| 281 |
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plp
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| 282 |
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rts
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; Mark pages as allocated
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| 285 |
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amp8:
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| 286 |
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tyx ; x= #pages to allocate
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| 287 |
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cpx #1
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| 288 |
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bne amp9
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txa ; flag indicates last page
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| 290 |
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bra amp10
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| 291 |
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amp9:
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| 292 |
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lda #0 ; flag indicates middle page
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amp10:
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jsr AllocMemPage ; allocate first page
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ld r4,r1 ; save virtual address of first page allocated
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dex
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| 297 |
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beq amp14
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| 298 |
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amp13:
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| 299 |
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cpx #1
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| 300 |
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bne amp15
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| 301 |
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txa
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| 302 |
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bra amp12
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| 303 |
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amp15:
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| 304 |
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lda #0
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| 305 |
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amp12:
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| 306 |
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jsr AllocMemPage
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| 307 |
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dex
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| 308 |
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bne amp13
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| 309 |
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amp14:
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| 310 |
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ld r1,r4 ; r1 = first virtual address
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| 311 |
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pop r4
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| 312 |
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ply
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| 313 |
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plx
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| 314 |
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plp
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| 315 |
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rts
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| 316 |
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| 317 |
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;------------------------------------------------------------------------------
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| 318 |
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; FreeMemPage:
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| 319 |
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;
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| 320 |
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; Free a single page of memory. This is an internal function called by
|
| 321 |
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; FreeMemPages(). Normally FreeMemPages() will be called to free up the
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| 322 |
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; entire run of pages. This function both unmarks the memory page in the
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| 323 |
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; page bitmap and invalidates the page in the MMU.
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| 324 |
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;
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| 325 |
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; Parameters:
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| 326 |
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; r1 = virtual memory address
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| 327 |
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;------------------------------------------------------------------------------
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| 328 |
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;
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| 329 |
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align 8
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| 330 |
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FreeMemPage:
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| 331 |
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pha
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| 332 |
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php
|
| 333 |
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phx
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| 334 |
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sei
|
| 335 |
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; First mark the page as available in the virtual page map.
|
| 336 |
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pha
|
| 337 |
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lsr r1,r1,#14
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| 338 |
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and #$1ff ; 512 virtual pages max
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| 339 |
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ldx RunningTCB
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| 340 |
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ldx TCB_mmu_map,x ; x = map #
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| 341 |
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asl r2,r2,#4 ; 16 words per map
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| 342 |
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bmc VPM_bitmap_b0,x ; clear both bits
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| 343 |
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bmc VPM_bitmap_b1,x
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| 344 |
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pla
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| 345 |
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; Mark the page available in the physical page map
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| 346 |
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pha
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| 347 |
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jsr VirtToPhys ; convert to a physical address
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| 348 |
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lsr r1,r1,#14
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| 349 |
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and #$7ff ; 2048 physical pages max
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| 350 |
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bmc PageMap
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| 351 |
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pla
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| 352 |
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; Now mark the MMU slot as empty
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| 353 |
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lsr r1,r1,#14 ; / 16kW r1 = page # now
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| 354 |
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and #$1ff ; 512 pages max
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| 355 |
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jsr SetAKEYForCurrentJob
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| 356 |
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tax
|
| 357 |
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lda #INV_PAGE
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| 358 |
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sta MMU,x
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| 359 |
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inc nPagesFree
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| 360 |
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plx
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| 361 |
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plp
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| 362 |
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pla
|
| 363 |
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rts
|
| 364 |
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| 365 |
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;------------------------------------------------------------------------------
|
| 366 |
|
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; FreeMemPages:
|
| 367 |
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;
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| 368 |
|
|
; Free up multiple pages of memory. The pages freed are a consecutive
|
| 369 |
|
|
; run of pages. A double-bit bitmap is used to identify where the run of
|
| 370 |
|
|
; pages ends. Bit code 00 indicates a unallocated page, 01 indicates an
|
| 371 |
|
|
; allocated page somewhere in the run, and 11 indicates the end of a run
|
| 372 |
|
|
; of allocated pages.
|
| 373 |
|
|
;
|
| 374 |
|
|
; Parameters:
|
| 375 |
|
|
; r1 = pointer to memory
|
| 376 |
|
|
;------------------------------------------------------------------------------
|
| 377 |
|
|
;
|
| 378 |
|
|
align 8
|
| 379 |
|
|
public FreeMemPages:
|
| 380 |
|
|
cmp #0x3fff ; test for a proper pointer
|
| 381 |
|
|
bls fmp5
|
| 382 |
|
|
pha
|
| 383 |
|
|
; Turn the memory pointer into a bit index
|
| 384 |
|
|
lsr r1,r1,#14 ; / 16kW acc = virtual page #
|
| 385 |
|
|
cmp #MAX_VIRTUAL_PAGE ; make sure index is sensible
|
| 386 |
|
|
bhs fmp4
|
| 387 |
|
|
phx
|
| 388 |
|
|
spl mem_sema + 1
|
| 389 |
|
|
ldx RunningTCB
|
| 390 |
|
|
ldx TCB_mmu_map,x
|
| 391 |
|
|
asl r2,r2,#4
|
| 392 |
|
|
fmp2:
|
| 393 |
|
|
bmt VPM_bitmap_b1,x ; Test to see if end of allocation
|
| 394 |
|
|
bne fmp3
|
| 395 |
|
|
asl r1,r1,#14 ; acc = virtual address
|
| 396 |
|
|
jsr FreeMemPage ;
|
| 397 |
|
|
lsr r1,r1,#14 ; acc = virtual page # again
|
| 398 |
|
|
ina
|
| 399 |
|
|
cmp #MAX_VIRTUAL_PAGE ; last 192 pages aren't freeable
|
| 400 |
|
|
blo fmp2
|
| 401 |
|
|
fmp3
|
| 402 |
|
|
; Clear the last bit
|
| 403 |
|
|
asl r1,r1,#14 ; acc = virtual address
|
| 404 |
|
|
jsr FreeMemPage ;
|
| 405 |
|
|
lsr r1,r1,#14 ; acc = virtual page # again
|
| 406 |
|
|
bmc VPM_bitmap_b1,x
|
| 407 |
|
|
stz mem_sema + 1
|
| 408 |
|
|
plx
|
| 409 |
|
|
fmp4:
|
| 410 |
|
|
pla
|
| 411 |
|
|
fmp5:
|
| 412 |
|
|
rts
|
| 413 |
|
|
|
| 414 |
|
|
;------------------------------------------------------------------------------
|
| 415 |
|
|
; Convert a virtual address to a physical address.
|
| 416 |
|
|
; Parameters:
|
| 417 |
|
|
; r1 = virtual address to translate
|
| 418 |
|
|
; Returns:
|
| 419 |
|
|
; r1 = physical address
|
| 420 |
|
|
;------------------------------------------------------------------------------
|
| 421 |
|
|
;
|
| 422 |
|
|
align 8
|
| 423 |
|
|
public VirtToPhys:
|
| 424 |
|
|
cmp #$3FFF ; page #0 is physical page #0
|
| 425 |
|
|
bls vtp2
|
| 426 |
|
|
cmp #$01FFFFFF ; outside of managed address bounds (ROM / IO)
|
| 427 |
|
|
bhi vtp2
|
| 428 |
|
|
phx
|
| 429 |
|
|
ldx CONFIGREC ; check if there is an MMU present
|
| 430 |
|
|
bit r2,#4096 ; if not, then virtual and physical addresses
|
| 431 |
|
|
beq vtp3 ; will match
|
| 432 |
|
|
phy
|
| 433 |
|
|
tay ; save original address
|
| 434 |
|
|
and r3,r3,#$FF803FFF ; mask off MMU managed address bits
|
| 435 |
|
|
jsr SetAKEYForCurrentJob
|
| 436 |
|
|
lsr r2,r1,#14 ; convert to MMU index
|
| 437 |
|
|
and r2,r2,#511 ; 512 mmu pages
|
| 438 |
|
|
lda MMU,x ; a = physical page#
|
| 439 |
|
|
beq vtp1 ; zero = invalid address translation
|
| 440 |
|
|
asl r1,r1,#14 ; *16kW
|
| 441 |
|
|
or r1,r1,r3 ; put back unmanaged address bits
|
| 442 |
|
|
vtp1:
|
| 443 |
|
|
ply
|
| 444 |
|
|
vtp3:
|
| 445 |
|
|
plx
|
| 446 |
|
|
vtp2:
|
| 447 |
|
|
rts
|
| 448 |
|
|
|
| 449 |
|
|
;------------------------------------------------------------------------------
|
| 450 |
|
|
; PhysToVirt
|
| 451 |
|
|
;
|
| 452 |
|
|
; Convert a physical address to a virtual address. A little more complex
|
| 453 |
|
|
; than converting virtual to physical addresses as the MMU map table must
|
| 454 |
|
|
; be searched for the physical page.
|
| 455 |
|
|
;
|
| 456 |
|
|
; Parameters:
|
| 457 |
|
|
; r1 = physical address to translate
|
| 458 |
|
|
; Returns:
|
| 459 |
|
|
; r1 = virtual address
|
| 460 |
|
|
;------------------------------------------------------------------------------
|
| 461 |
|
|
;
|
| 462 |
|
|
align 8
|
| 463 |
|
|
public PhysToVirt:
|
| 464 |
|
|
cmp #$3FFF ; first check for direct translations
|
| 465 |
|
|
bls ptv3 ; outside of the MMU managed range
|
| 466 |
|
|
cmp #$01FFFFFF
|
| 467 |
|
|
bhi ptv3
|
| 468 |
|
|
phx
|
| 469 |
|
|
ldx CONFIGREC ; check if there is an MMU present
|
| 470 |
|
|
bit r2,#4096 ; if not, then virtual and physical addresses
|
| 471 |
|
|
beq ptv4 ; will match
|
| 472 |
|
|
phy
|
| 473 |
|
|
jsr SetAKEYForCurrentJob
|
| 474 |
|
|
tay
|
| 475 |
|
|
and r3,r3,#$FF803FFF ; mask off MMU managed address bits
|
| 476 |
|
|
lsr r1,r1,#14 ; /16k to get index
|
| 477 |
|
|
and r1,r1,#$7ff ; 2048 pages max
|
| 478 |
|
|
ldx #0
|
| 479 |
|
|
ptv2:
|
| 480 |
|
|
cmp MMU,x
|
| 481 |
|
|
beq ptv1
|
| 482 |
|
|
inx
|
| 483 |
|
|
cpx #512
|
| 484 |
|
|
bne ptv2
|
| 485 |
|
|
; Return NULL pointer if address translation fails
|
| 486 |
|
|
ply
|
| 487 |
|
|
plx
|
| 488 |
|
|
lda #0
|
| 489 |
|
|
rts
|
| 490 |
|
|
ptv1:
|
| 491 |
|
|
asl r1,r2,#14 ; * 16k
|
| 492 |
|
|
or r1,r1,r3 ; put back unmanaged address bits
|
| 493 |
|
|
ply
|
| 494 |
|
|
ptv4:
|
| 495 |
|
|
plx
|
| 496 |
|
|
ptv3:
|
| 497 |
|
|
rts
|
| 498 |
|
|
|
| 499 |
|
|
; ============================================================================
|
| 500 |
|
|
; Heap related functions.
|
| 501 |
|
|
;
|
| 502 |
|
|
; The heap is managed as a doublely linked list of memory blocks.
|
| 503 |
|
|
; ============================================================================
|
| 504 |
|
|
|
| 505 |
|
|
align 8
|
| 506 |
|
|
public InitHeap:
|
| 507 |
|
|
lda RunningTCB
|
| 508 |
|
|
ldx TCB_HeapStart,r1
|
| 509 |
|
|
ldy TCB_HeapEnd,r1
|
| 510 |
|
|
lda #$4D454D20
|
| 511 |
|
|
sta MEM_CHK,x
|
| 512 |
|
|
sta MEM_FLAG,x
|
| 513 |
|
|
lda #$6D656D20 ; mark the last block as allocated
|
| 514 |
|
|
sta MEM_CHK,y
|
| 515 |
|
|
sta MEM_FLAG,y
|
| 516 |
|
|
lda #0
|
| 517 |
|
|
sta MEM_PREV,x ; prev of first MEMHDR
|
| 518 |
|
|
sty MEM_NEXT,x
|
| 519 |
|
|
sta MEM_NEXT,y
|
| 520 |
|
|
stx MEM_PREV,y
|
| 521 |
|
|
rts
|
| 522 |
|
|
|
| 523 |
|
|
;------------------------------------------------------------------------------
|
| 524 |
|
|
; Allocate memory from the heap.
|
| 525 |
|
|
; Each task has it's own memory heap.
|
| 526 |
|
|
;------------------------------------------------------------------------------
|
| 527 |
|
|
align 8
|
| 528 |
|
|
public MemAlloc:
|
| 529 |
|
|
phx
|
| 530 |
|
|
phy
|
| 531 |
|
|
push r4
|
| 532 |
|
|
ldx RunningTCB
|
| 533 |
|
|
ldx TCB_HeapStart,x
|
| 534 |
|
|
mema4:
|
| 535 |
|
|
ldy MEM_FLAG,x ; Check the flag word to see if this block is available
|
| 536 |
|
|
cpy #$4D454D20
|
| 537 |
|
|
bne mema1 ; block not available, go to next block
|
| 538 |
|
|
ld r4,MEM_NEXT,x ; compute the size of this block
|
| 539 |
|
|
sub r4,r4,r2
|
| 540 |
|
|
sub r4,r4,#4 ; minus size of block header
|
| 541 |
|
|
cmp r1,r4 ; is the block large enough ?
|
| 542 |
|
|
bmi mema2 ; if yes, go allocate
|
| 543 |
|
|
mema1:
|
| 544 |
|
|
ldx MEM_NEXT,x ; go to the next block
|
| 545 |
|
|
beq mema3 ; if no more blocks, out of memory error
|
| 546 |
|
|
bra mema4
|
| 547 |
|
|
mema2:
|
| 548 |
|
|
ldy #$6D656D20
|
| 549 |
|
|
sty MEM_FLAG,x
|
| 550 |
|
|
sub r4,r4,r1
|
| 551 |
|
|
cmp r4,#4 ; is the block large enough to split
|
| 552 |
|
|
bpl memaSplit
|
| 553 |
|
|
txa
|
| 554 |
|
|
add #4 ; point to payload area
|
| 555 |
|
|
pop r4
|
| 556 |
|
|
ply
|
| 557 |
|
|
plx
|
| 558 |
|
|
rts
|
| 559 |
|
|
mema3: ; insufficient memory
|
| 560 |
|
|
pop r4
|
| 561 |
|
|
ply
|
| 562 |
|
|
plx
|
| 563 |
|
|
lda #0
|
| 564 |
|
|
rts
|
| 565 |
|
|
memaSplit:
|
| 566 |
|
|
add r4,r1,r2
|
| 567 |
|
|
add r4,#4
|
| 568 |
|
|
ldy #$4D454D20
|
| 569 |
|
|
sty (r4)
|
| 570 |
|
|
sty MEM_FLAG,r4
|
| 571 |
|
|
stx MEM_PREV,r4
|
| 572 |
|
|
ldy MEM_NEXT,x
|
| 573 |
|
|
sty MEM_NEXT,r4
|
| 574 |
|
|
st r4,MEM_PREV,y
|
| 575 |
|
|
ld r1,r4
|
| 576 |
|
|
add #4
|
| 577 |
|
|
pop r4
|
| 578 |
|
|
ply
|
| 579 |
|
|
plx
|
| 580 |
|
|
rts
|
| 581 |
|
|
|
| 582 |
|
|
;------------------------------------------------------------------------------
|
| 583 |
|
|
; Free previously allocated memory. Recombine with next and previous blocks
|
| 584 |
|
|
; if they are free as well.
|
| 585 |
|
|
;------------------------------------------------------------------------------
|
| 586 |
|
|
align 8
|
| 587 |
|
|
public MemFree:
|
| 588 |
|
|
cmp #4 ; null pointer ?
|
| 589 |
|
|
blo memf2
|
| 590 |
|
|
phx
|
| 591 |
|
|
phy
|
| 592 |
|
|
sub #4 ; backup to header area
|
| 593 |
|
|
ldx MEM_FLAG,r1
|
| 594 |
|
|
cpx #$6D656D20 ; is the block allocated ?
|
| 595 |
|
|
bne memf1
|
| 596 |
|
|
ldx #$4D454D20
|
| 597 |
|
|
stx MEM_FLAG,r1 ; mark block as free
|
| 598 |
|
|
ldx MEM_PREV,r1 ; is the previous block free ?
|
| 599 |
|
|
beq memf3 ; no previous block
|
| 600 |
|
|
ldy MEM_FLAG,x
|
| 601 |
|
|
cpy #$4D454D20
|
| 602 |
|
|
bne memf3 ; the previous block is not free
|
| 603 |
|
|
ldy MEM_NEXT,r1
|
| 604 |
|
|
sty MEM_NEXT,x
|
| 605 |
|
|
beq memf1 ; no next block
|
| 606 |
|
|
stx MEM_PREV,y
|
| 607 |
|
|
memf3:
|
| 608 |
|
|
ldy MEM_NEXT,r1
|
| 609 |
|
|
ldx MEM_FLAG,y
|
| 610 |
|
|
cpx #$4D454D20
|
| 611 |
|
|
bne memf1 ; next block not free
|
| 612 |
|
|
ldx MEM_PREV,r1
|
| 613 |
|
|
stx MEM_PREV,y
|
| 614 |
|
|
beq memf1 ; no previous block
|
| 615 |
|
|
sty MEM_NEXT,x
|
| 616 |
|
|
memf1:
|
| 617 |
|
|
ply
|
| 618 |
|
|
plx
|
| 619 |
|
|
memf2:
|
| 620 |
|
|
rts
|
| 621 |
|
|
|
| 622 |
|
|
;------------------------------------------------------------------------------
|
| 623 |
|
|
; Report the amount of system memory free. Counts up the number of
|
| 624 |
|
|
; unallocated pages in the page bitmap.
|
| 625 |
|
|
;------------------------------------------------------------------------------
|
| 626 |
|
|
;
|
| 627 |
|
|
public ReportMemFree:
|
| 628 |
|
|
jsr CRLF
|
| 629 |
|
|
lda #' '
|
| 630 |
|
|
jsr DisplayChar
|
| 631 |
|
|
lda #0
|
| 632 |
|
|
tay
|
| 633 |
|
|
rmf2:
|
| 634 |
|
|
bmt PageMap
|
| 635 |
|
|
bne rmf1
|
| 636 |
|
|
iny
|
| 637 |
|
|
rmf1:
|
| 638 |
|
|
ina
|
| 639 |
|
|
cmp #2048
|
| 640 |
|
|
blo rmf2
|
| 641 |
|
|
tya
|
| 642 |
|
|
asl r1,r1,#14 ; 16kW per bit
|
| 643 |
|
|
ldx #5
|
| 644 |
|
|
jsr PRTNUM
|
| 645 |
|
|
lea r1,msgMemFree
|
| 646 |
|
|
jsr DisplayStringB
|
| 647 |
|
|
rts
|
| 648 |
|
|
|
| 649 |
|
|
msgMemFree:
|
| 650 |
|
|
db " words free",CR,LF,0
|
| 651 |
|
|
|
| 652 |
|
|
;==============================================================================
|
| 653 |
|
|
; Memory Management routines follow.
|
| 654 |
|
|
;==============================================================================
|
| 655 |
|
|
|
| 656 |
|
|
;------------------------------------------------------------------------------
|
| 657 |
|
|
; brk
|
| 658 |
|
|
; Establish a new program break
|
| 659 |
|
|
;
|
| 660 |
|
|
; Parameters:
|
| 661 |
|
|
; r1 = new program break address
|
| 662 |
|
|
;------------------------------------------------------------------------------
|
| 663 |
|
|
;
|
| 664 |
|
|
public _brk:
|
| 665 |
|
|
phx
|
| 666 |
|
|
push r4
|
| 667 |
|
|
push r5
|
| 668 |
|
|
push r6
|
| 669 |
|
|
ldx RunningTCB
|
| 670 |
|
|
ld r4,TCB_ASID,x
|
| 671 |
|
|
st r4,MMU_AKEY
|
| 672 |
|
|
ld r4,TCB_npages,x
|
| 673 |
|
|
lsr r1,r1,#14
|
| 674 |
|
|
add r1,r1,#1
|
| 675 |
|
|
cmp r1,r4
|
| 676 |
|
|
beq brk6 ; allocation isn't changing
|
| 677 |
|
|
blo brk1 ; reducing allocation
|
| 678 |
|
|
|
| 679 |
|
|
; Here we're increasing the amount of memory allocated to the program.
|
| 680 |
|
|
;
|
| 681 |
|
|
cmp r1,#320 ; max 320 RAM pages
|
| 682 |
|
|
bhi brk2
|
| 683 |
|
|
sub r1,r1,r4 ; number of new pages
|
| 684 |
|
|
cmp r1,mem_pages_free ; are there enough free pages ?
|
| 685 |
|
|
bhi brk2
|
| 686 |
|
|
ld r5,mem_pages_free
|
| 687 |
|
|
sub r5,r5,r1
|
| 688 |
|
|
st r5,mem_pages_free
|
| 689 |
|
|
ld r6,r1 ; r6 = number of pages to allocate
|
| 690 |
|
|
add r1,r1,r4 ; get back value of address
|
| 691 |
|
|
sta TCB_npages,x
|
| 692 |
|
|
lda #0
|
| 693 |
|
|
brk5:
|
| 694 |
|
|
bmt PageMap ; test if page is free
|
| 695 |
|
|
bne brk4 ; no, go for next page
|
| 696 |
|
|
bms PageMap ; allocate the page
|
| 697 |
|
|
sta MMU,r4 ; store the page number in the MMU table
|
| 698 |
|
|
add r4,#1 ; move to next MMU entry
|
| 699 |
|
|
sub r6,#1 ; decrement count of needed
|
| 700 |
|
|
beq brk6 ; we're done if count = 0
|
| 701 |
|
|
brk4:
|
| 702 |
|
|
ina
|
| 703 |
|
|
cmp #2048
|
| 704 |
|
|
blo brk5
|
| 705 |
|
|
|
| 706 |
|
|
; Here there was an OS or hardware error
|
| 707 |
|
|
; According to mem_pages_free there should have been enough free pages
|
| 708 |
|
|
; to fulfill the request. Something is corrupt.
|
| 709 |
|
|
;
|
| 710 |
|
|
|
| 711 |
|
|
; Here we are reducing the program break, which means freeing up pages of
|
| 712 |
|
|
; memory.
|
| 713 |
|
|
brk1:
|
| 714 |
|
|
sta TCB_npages,x
|
| 715 |
|
|
add r5,r1,#1 ; move to page after last page
|
| 716 |
|
|
brk7:
|
| 717 |
|
|
cmp r5,r4 ; are we done freeing pages ?
|
| 718 |
|
|
bhi brk6
|
| 719 |
|
|
lda MMU,r5 ; get the page to free
|
| 720 |
|
|
bmc PageMap ; free the page
|
| 721 |
|
|
inc mem_pages_free
|
| 722 |
|
|
add r5,#1
|
| 723 |
|
|
bra brk7
|
| 724 |
|
|
|
| 725 |
|
|
; Successful return
|
| 726 |
|
|
brk6:
|
| 727 |
|
|
pop r6
|
| 728 |
|
|
pop r5
|
| 729 |
|
|
pop r4
|
| 730 |
|
|
plx
|
| 731 |
|
|
lda #0
|
| 732 |
|
|
rts
|
| 733 |
|
|
|
| 734 |
|
|
; Return insufficient memory error
|
| 735 |
|
|
;
|
| 736 |
|
|
brk2:
|
| 737 |
|
|
lda #E_NoMem
|
| 738 |
|
|
sta TCB_errno,x
|
| 739 |
|
|
pop r6
|
| 740 |
|
|
pop r5
|
| 741 |
|
|
pop r4
|
| 742 |
|
|
plx
|
| 743 |
|
|
lda #-1
|
| 744 |
|
|
rts
|
| 745 |
|
|
|
| 746 |
|
|
;------------------------------------------------------------------------------
|
| 747 |
|
|
; Parameters:
|
| 748 |
|
|
; r1 = change in memory allocation
|
| 749 |
|
|
;------------------------------------------------------------------------------
|
| 750 |
|
|
public _sbrk:
|
| 751 |
|
|
phx
|
| 752 |
|
|
push r4
|
| 753 |
|
|
push r5
|
| 754 |
|
|
ldx RunningTCB
|
| 755 |
|
|
ld r4,TCB_npages,x ; get the current memory allocation
|
| 756 |
|
|
cmp r1,#0 ; zero difference = get old brk address
|
| 757 |
|
|
beq sbrk2
|
| 758 |
|
|
asl r5,r4,#14 ; convert to words
|
| 759 |
|
|
add r1,r1,r5 ; +/- amount
|
| 760 |
|
|
jsr _brk
|
| 761 |
|
|
cmp r1,#-1
|
| 762 |
|
|
bne sbrk2
|
| 763 |
|
|
|
| 764 |
|
|
; Failure return, return -1
|
| 765 |
|
|
;
|
| 766 |
|
|
pop r5
|
| 767 |
|
|
pop r4
|
| 768 |
|
|
plx
|
| 769 |
|
|
rts
|
| 770 |
|
|
|
| 771 |
|
|
; Successful return, return the old break address
|
| 772 |
|
|
;
|
| 773 |
|
|
sbrk2:
|
| 774 |
|
|
ld r1,r4
|
| 775 |
|
|
asl r1,r1,#14
|
| 776 |
|
|
pop r5
|
| 777 |
|
|
pop r4
|
| 778 |
|
|
plx
|
| 779 |
|
|
rts
|
| 780 |
|
|
|
