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SHeap/ReadMe
This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.
Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.
| Tape/disk: | Home » Personal collection » Acorn hard disk » unzip_tools » !Infozip |
| Filename: | SHeap/ReadMe |
| Read OK: | ✔ |
| File size: | 0A88 bytes |
| Load address: | 0000 |
| Exec address: | 0000 |
File contents
The Sliding Heap module is � Steven Haslam 1992 and is distributed under the GNU Public Licence. You will need the procedures in the SHeap BASIC library, or similar, to use it. It creates and manages a sliding heap of blocks of memory, claimed from a program's Wimpslot as necessary, thus avoiding the fragmentation caused by repeatedly claiming and releasing memory from the RMA. The module works under RISC OS 2 and RISC OS 3�1, and is compatible with RISC OS 3�5 and greater, and StrongARM, although dynamic areas can be used to perform the same task on such systems. This new release of SlidingHeap (version 2.11) has been reconstructed from a disassembly, in the absence of the original source code. The module should work in 32-bit ARM modes, and therefore has been flagged as compatible with RISC OS 5. For further information contact chrisbazley@bigfoot.com. 17th January 2003 Changes to the accompanying BASIC library ----------------------------------------- � A new function has been added to the BASIC library - FNsliding_block_size(anchor%), which returns the current size of the specified block. � Two new procedures have been added - PROCverify_heap, which enables the programmer to force a explicit check for corruption of the sliding heap at any point in his code, and PROCincreaseslots, which allows the programmer to increase the number of available slots in the heap, or to read its current setting. � PROCheapsinfo now takes a parameter - PROCheapsinfo(address%), where address% points to a buffer of length 256 bytes. As a consequence, the library no longer relies on the (undocumented) existence of a block with a certain given name! � Variables have been made LOCAL wherever possible, and global variables use the prefix 'sh_', e.g. 'sh_heap_trigger%'. � PROCdestroyheaps now ensures that all anchors in use are reset to zero before the heap is destroyed, making it 'safe' to reuse them after a subsequent PROCinitheaps. Module history -------------- Version 2.01 � Most SWIs no longer corrupt R0. � SWIs now *do* preserve flags in 26-bit mode (although not in new 32-bit mode) - which they never did before! � A few optimisations, i.e. SUBS R1,R1,#1:BNE in place of SUB R1,R1,#1:CMP R1,#0:BNE Version 2.10 (18 Nov 2002) � Numbers of heap slots available/used are now reported via OS_ConvertCardinal (e.g. "2048") rather than OS_ConvertSpacedCardinal (e.g. "2 048"), as the leading digit proved too easily overlooked. � New SWI added - SlidingHeap_IncreaseSlots. This allows programs to use a indeterminate number of blocks, without having to set an upper limit at the time of initialisation. Version 2.11 (16 Dec 2002) � A few more SUBS optimisations.
00000000 54 68 65 20 53 6c 69 64 69 6e 67 20 48 65 61 70 |The Sliding Heap| 00000010 20 6d 6f 64 75 6c 65 20 69 73 20 a9 20 53 74 65 | module is . Ste| 00000020 76 65 6e 20 48 61 73 6c 61 6d 20 31 39 39 32 20 |ven Haslam 1992 | 00000030 61 6e 64 20 69 73 20 64 69 73 74 72 69 62 75 74 |and is distribut| 00000040 65 64 20 75 6e 64 65 72 20 74 68 65 20 47 4e 55 |ed under the GNU| 00000050 20 50 75 62 6c 69 63 20 4c 69 63 65 6e 63 65 2e | Public Licence.| 00000060 20 20 20 59 6f 75 20 77 69 6c 6c 20 6e 65 65 64 | You will need| 00000070 20 74 68 65 20 70 72 6f 63 65 64 75 72 65 73 20 | the procedures | 00000080 69 6e 20 74 68 65 20 53 48 65 61 70 20 42 41 53 |in the SHeap BAS| 00000090 49 43 20 6c 69 62 72 61 72 79 2c 20 6f 72 20 73 |IC library, or s| 000000a0 69 6d 69 6c 61 72 2c 20 74 6f 20 75 73 65 20 69 |imilar, to use i| 000000b0 74 2e 0a 0a 49 74 20 63 72 65 61 74 65 73 20 61 |t...It creates a| 000000c0 6e 64 20 6d 61 6e 61 67 65 73 20 61 20 73 6c 69 |nd manages a sli| 000000d0 64 69 6e 67 20 68 65 61 70 20 6f 66 20 62 6c 6f |ding heap of blo| 000000e0 63 6b 73 20 6f 66 20 6d 65 6d 6f 72 79 2c 20 63 |cks of memory, c| 000000f0 6c 61 69 6d 65 64 20 66 72 6f 6d 20 61 20 70 72 |laimed from a pr| 00000100 6f 67 72 61 6d 27 73 20 57 69 6d 70 73 6c 6f 74 |ogram's Wimpslot| 00000110 20 61 73 20 6e 65 63 65 73 73 61 72 79 2c 20 74 | as necessary, t| 00000120 68 75 73 20 61 76 6f 69 64 69 6e 67 20 74 68 65 |hus avoiding the| 00000130 20 66 72 61 67 6d 65 6e 74 61 74 69 6f 6e 20 63 | fragmentation c| 00000140 61 75 73 65 64 20 62 79 20 72 65 70 65 61 74 65 |aused by repeate| 00000150 64 6c 79 20 63 6c 61 69 6d 69 6e 67 20 61 6e 64 |dly claiming and| 00000160 20 72 65 6c 65 61 73 69 6e 67 20 6d 65 6d 6f 72 | releasing memor| 00000170 79 20 66 72 6f 6d 20 74 68 65 20 52 4d 41 2e 0a |y from the RMA..| 00000180 54 68 65 20 6d 6f 64 75 6c 65 20 77 6f 72 6b 73 |The module works| 00000190 20 75 6e 64 65 72 20 52 49 53 43 20 4f 53 20 32 | under RISC OS 2| 000001a0 20 61 6e 64 20 52 49 53 43 20 4f 53 20 33 b7 31 | and RISC OS 3.1| 000001b0 2c 20 61 6e 64 20 69 73 20 63 6f 6d 70 61 74 69 |, and is compati| 000001c0 62 6c 65 20 77 69 74 68 20 52 49 53 43 20 4f 53 |ble with RISC OS| 000001d0 20 33 b7 35 20 61 6e 64 20 67 72 65 61 74 65 72 | 3.5 and greater| 000001e0 2c 20 61 6e 64 20 53 74 72 6f 6e 67 41 52 4d 2c |, and StrongARM,| 000001f0 20 61 6c 74 68 6f 75 67 68 20 64 79 6e 61 6d 69 | although dynami| 00000200 63 20 61 72 65 61 73 20 63 61 6e 20 62 65 20 75 |c areas can be u| 00000210 73 65 64 20 74 6f 20 70 65 72 66 6f 72 6d 20 74 |sed to perform t| 00000220 68 65 20 73 61 6d 65 20 74 61 73 6b 20 6f 6e 20 |he same task on | 00000230 73 75 63 68 20 73 79 73 74 65 6d 73 2e 0a 0a 54 |such systems...T| 00000240 68 69 73 20 6e 65 77 20 72 65 6c 65 61 73 65 20 |his new release | 00000250 6f 66 20 53 6c 69 64 69 6e 67 48 65 61 70 20 28 |of SlidingHeap (| 00000260 76 65 72 73 69 6f 6e 20 32 2e 31 31 29 20 68 61 |version 2.11) ha| 00000270 73 20 62 65 65 6e 20 72 65 63 6f 6e 73 74 72 75 |s been reconstru| 00000280 63 74 65 64 20 66 72 6f 6d 20 61 20 64 69 73 61 |cted from a disa| 00000290 73 73 65 6d 62 6c 79 2c 20 69 6e 20 74 68 65 20 |ssembly, in the | 000002a0 61 62 73 65 6e 63 65 20 6f 66 20 74 68 65 20 6f |absence of the o| 000002b0 72 69 67 69 6e 61 6c 20 73 6f 75 72 63 65 20 63 |riginal source c| 000002c0 6f 64 65 2e 20 54 68 65 20 6d 6f 64 75 6c 65 20 |ode. The module | 000002d0 73 68 6f 75 6c 64 20 77 6f 72 6b 20 69 6e 20 33 |should work in 3| 000002e0 32 2d 62 69 74 20 41 52 4d 20 6d 6f 64 65 73 2c |2-bit ARM modes,| 000002f0 20 61 6e 64 20 74 68 65 72 65 66 6f 72 65 20 68 | and therefore h| 00000300 61 73 20 62 65 65 6e 20 66 6c 61 67 67 65 64 20 |as been flagged | 00000310 61 73 20 63 6f 6d 70 61 74 69 62 6c 65 20 77 69 |as compatible wi| 00000320 74 68 20 52 49 53 43 20 4f 53 20 35 2e 20 20 46 |th RISC OS 5. F| 00000330 6f 72 20 66 75 72 74 68 65 72 20 69 6e 66 6f 72 |or further infor| 00000340 6d 61 74 69 6f 6e 20 63 6f 6e 74 61 63 74 20 63 |mation contact c| 00000350 68 72 69 73 62 61 7a 6c 65 79 40 62 69 67 66 6f |hrisbazley@bigfo| 00000360 6f 74 2e 63 6f 6d 2e 0a 0a 31 37 74 68 20 4a 61 |ot.com...17th Ja| 00000370 6e 75 61 72 79 20 32 30 30 33 0a 0a 43 68 61 6e |nuary 2003..Chan| 00000380 67 65 73 20 74 6f 20 74 68 65 20 61 63 63 6f 6d |ges to the accom| 00000390 70 61 6e 79 69 6e 67 20 42 41 53 49 43 20 6c 69 |panying BASIC li| 000003a0 62 72 61 72 79 0a 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |brary.----------| 000003b0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------| 000003c0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 0a |---------------.| 000003d0 8f 20 20 41 20 6e 65 77 20 66 75 6e 63 74 69 6f |. A new functio| 000003e0 6e 20 68 61 73 20 62 65 65 6e 20 61 64 64 65 64 |n has been added| 000003f0 20 74 6f 20 74 68 65 20 42 41 53 49 43 20 6c 69 | to the BASIC li| 00000400 62 72 61 72 79 20 2d 20 46 4e 73 6c 69 64 69 6e |brary - FNslidin| 00000410 67 5f 62 6c 6f 63 6b 5f 73 69 7a 65 28 61 6e 63 |g_block_size(anc| 00000420 68 6f 72 25 29 2c 20 77 68 69 63 68 20 72 65 74 |hor%), which ret| 00000430 75 72 6e 73 20 74 68 65 20 63 75 72 72 65 6e 74 |urns the current| 00000440 20 73 69 7a 65 20 6f 66 20 74 68 65 20 73 70 65 | size of the spe| 00000450 63 69 66 69 65 64 20 62 6c 6f 63 6b 2e 0a 8f 20 |cified block... | 00000460 54 77 6f 20 6e 65 77 20 70 72 6f 63 65 64 75 72 |Two new procedur| 00000470 65 73 20 68 61 76 65 20 62 65 65 6e 20 61 64 64 |es have been add| 00000480 65 64 20 2d 20 50 52 4f 43 76 65 72 69 66 79 5f |ed - PROCverify_| 00000490 68 65 61 70 2c 20 77 68 69 63 68 20 65 6e 61 62 |heap, which enab| 000004a0 6c 65 73 20 74 68 65 20 70 72 6f 67 72 61 6d 6d |les the programm| 000004b0 65 72 20 74 6f 20 66 6f 72 63 65 20 61 20 65 78 |er to force a ex| 000004c0 70 6c 69 63 69 74 20 63 68 65 63 6b 20 66 6f 72 |plicit check for| 000004d0 20 63 6f 72 72 75 70 74 69 6f 6e 20 6f 66 20 74 | corruption of t| 000004e0 68 65 20 73 6c 69 64 69 6e 67 20 68 65 61 70 20 |he sliding heap | 000004f0 61 74 20 61 6e 79 20 70 6f 69 6e 74 20 69 6e 20 |at any point in | 00000500 68 69 73 20 63 6f 64 65 2c 20 61 6e 64 20 50 52 |his code, and PR| 00000510 4f 43 69 6e 63 72 65 61 73 65 73 6c 6f 74 73 2c |OCincreaseslots,| 00000520 20 77 68 69 63 68 20 61 6c 6c 6f 77 73 20 74 68 | which allows th| 00000530 65 20 70 72 6f 67 72 61 6d 6d 65 72 20 74 6f 20 |e programmer to | 00000540 69 6e 63 72 65 61 73 65 20 74 68 65 20 6e 75 6d |increase the num| 00000550 62 65 72 20 6f 66 20 61 76 61 69 6c 61 62 6c 65 |ber of available| 00000560 20 73 6c 6f 74 73 20 69 6e 20 74 68 65 20 68 65 | slots in the he| 00000570 61 70 2c 20 6f 72 20 74 6f 20 72 65 61 64 20 69 |ap, or to read i| 00000580 74 73 20 63 75 72 72 65 6e 74 20 73 65 74 74 69 |ts current setti| 00000590 6e 67 2e 0a 8f 20 20 50 52 4f 43 68 65 61 70 73 |ng... PROCheaps| 000005a0 69 6e 66 6f 20 6e 6f 77 20 74 61 6b 65 73 20 61 |info now takes a| 000005b0 20 70 61 72 61 6d 65 74 65 72 20 2d 20 50 52 4f | parameter - PRO| 000005c0 43 68 65 61 70 73 69 6e 66 6f 28 61 64 64 72 65 |Cheapsinfo(addre| 000005d0 73 73 25 29 2c 20 77 68 65 72 65 20 61 64 64 72 |ss%), where addr| 000005e0 65 73 73 25 20 70 6f 69 6e 74 73 20 74 6f 20 61 |ess% points to a| 000005f0 20 62 75 66 66 65 72 20 6f 66 20 6c 65 6e 67 74 | buffer of lengt| 00000600 68 20 32 35 36 20 62 79 74 65 73 2e 20 20 20 41 |h 256 bytes. A| 00000610 73 20 61 20 63 6f 6e 73 65 71 75 65 6e 63 65 2c |s a consequence,| 00000620 20 74 68 65 20 6c 69 62 72 61 72 79 20 6e 6f 20 | the library no | 00000630 6c 6f 6e 67 65 72 20 72 65 6c 69 65 73 20 6f 6e |longer relies on| 00000640 20 74 68 65 20 28 75 6e 64 6f 63 75 6d 65 6e 74 | the (undocument| 00000650 65 64 29 20 65 78 69 73 74 65 6e 63 65 20 6f 66 |ed) existence of| 00000660 20 61 20 62 6c 6f 63 6b 20 77 69 74 68 20 61 20 | a block with a | 00000670 63 65 72 74 61 69 6e 20 67 69 76 65 6e 20 6e 61 |certain given na| 00000680 6d 65 21 0a 8f 20 20 56 61 72 69 61 62 6c 65 73 |me!.. Variables| 00000690 20 68 61 76 65 20 62 65 65 6e 20 6d 61 64 65 20 | have been made | 000006a0 4c 4f 43 41 4c 20 77 68 65 72 65 76 65 72 20 70 |LOCAL wherever p| 000006b0 6f 73 73 69 62 6c 65 2c 20 61 6e 64 20 67 6c 6f |ossible, and glo| 000006c0 62 61 6c 20 76 61 72 69 61 62 6c 65 73 20 75 73 |bal variables us| 000006d0 65 20 74 68 65 20 70 72 65 66 69 78 20 27 73 68 |e the prefix 'sh| 000006e0 5f 27 2c 20 65 2e 67 2e 20 27 73 68 5f 68 65 61 |_', e.g. 'sh_hea| 000006f0 70 5f 74 72 69 67 67 65 72 25 27 2e 0a 8f 20 20 |p_trigger%'... | 00000700 50 52 4f 43 64 65 73 74 72 6f 79 68 65 61 70 73 |PROCdestroyheaps| 00000710 20 6e 6f 77 20 65 6e 73 75 72 65 73 20 74 68 61 | now ensures tha| 00000720 74 20 61 6c 6c 20 61 6e 63 68 6f 72 73 20 69 6e |t all anchors in| 00000730 20 75 73 65 20 61 72 65 20 72 65 73 65 74 20 74 | use are reset t| 00000740 6f 20 7a 65 72 6f 20 62 65 66 6f 72 65 20 74 68 |o zero before th| 00000750 65 20 68 65 61 70 20 69 73 20 64 65 73 74 72 6f |e heap is destro| 00000760 79 65 64 2c 20 6d 61 6b 69 6e 67 20 69 74 20 27 |yed, making it '| 00000770 73 61 66 65 27 20 74 6f 20 72 65 75 73 65 20 74 |safe' to reuse t| 00000780 68 65 6d 20 61 66 74 65 72 20 61 20 73 75 62 73 |hem after a subs| 00000790 65 71 75 65 6e 74 20 50 52 4f 43 69 6e 69 74 68 |equent PROCinith| 000007a0 65 61 70 73 2e 0a 0a 4d 6f 64 75 6c 65 20 68 69 |eaps...Module hi| 000007b0 73 74 6f 72 79 0a 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |story.----------| 000007c0 2d 2d 2d 2d 0a 56 65 72 73 69 6f 6e 20 32 2e 30 |----.Version 2.0| 000007d0 31 0a 8f 20 4d 6f 73 74 20 53 57 49 73 20 6e 6f |1.. Most SWIs no| 000007e0 20 6c 6f 6e 67 65 72 20 63 6f 72 72 75 70 74 20 | longer corrupt | 000007f0 52 30 2e 0a 8f 20 53 57 49 73 20 6e 6f 77 20 2a |R0... SWIs now *| 00000800 64 6f 2a 20 70 72 65 73 65 72 76 65 20 66 6c 61 |do* preserve fla| 00000810 67 73 20 69 6e 20 32 36 2d 62 69 74 20 6d 6f 64 |gs in 26-bit mod| 00000820 65 20 28 61 6c 74 68 6f 75 67 68 20 6e 6f 74 20 |e (although not | 00000830 69 6e 20 6e 65 77 20 33 32 2d 62 69 74 20 6d 6f |in new 32-bit mo| 00000840 64 65 29 20 2d 20 77 68 69 63 68 20 74 68 65 79 |de) - which they| 00000850 20 6e 65 76 65 72 20 64 69 64 20 62 65 66 6f 72 | never did befor| 00000860 65 21 0a 8f 20 41 20 66 65 77 20 6f 70 74 69 6d |e!.. A few optim| 00000870 69 73 61 74 69 6f 6e 73 2c 20 69 2e 65 2e 20 53 |isations, i.e. S| 00000880 55 42 53 20 52 31 2c 52 31 2c 23 31 3a 42 4e 45 |UBS R1,R1,#1:BNE| 00000890 20 69 6e 20 70 6c 61 63 65 20 6f 66 20 53 55 42 | in place of SUB| 000008a0 20 52 31 2c 52 31 2c 23 31 3a 43 4d 50 20 52 31 | R1,R1,#1:CMP R1| 000008b0 2c 23 30 3a 42 4e 45 0a 0a 56 65 72 73 69 6f 6e |,#0:BNE..Version| 000008c0 20 32 2e 31 30 20 28 31 38 20 4e 6f 76 20 32 30 | 2.10 (18 Nov 20| 000008d0 30 32 29 0a 8f 20 4e 75 6d 62 65 72 73 20 6f 66 |02).. Numbers of| 000008e0 20 68 65 61 70 20 73 6c 6f 74 73 20 61 76 61 69 | heap slots avai| 000008f0 6c 61 62 6c 65 2f 75 73 65 64 20 61 72 65 20 6e |lable/used are n| 00000900 6f 77 20 72 65 70 6f 72 74 65 64 20 76 69 61 20 |ow reported via | 00000910 4f 53 5f 43 6f 6e 76 65 72 74 43 61 72 64 69 6e |OS_ConvertCardin| 00000920 61 6c 20 28 65 2e 67 2e 20 22 32 30 34 38 22 29 |al (e.g. "2048")| 00000930 20 72 61 74 68 65 72 20 74 68 61 6e 20 4f 53 5f | rather than OS_| 00000940 43 6f 6e 76 65 72 74 53 70 61 63 65 64 43 61 72 |ConvertSpacedCar| 00000950 64 69 6e 61 6c 20 28 65 2e 67 2e 20 22 32 20 30 |dinal (e.g. "2 0| 00000960 34 38 22 29 2c 20 61 73 20 74 68 65 20 6c 65 61 |48"), as the lea| 00000970 64 69 6e 67 20 64 69 67 69 74 20 70 72 6f 76 65 |ding digit prove| 00000980 64 20 74 6f 6f 20 65 61 73 69 6c 79 20 6f 76 65 |d too easily ove| 00000990 72 6c 6f 6f 6b 65 64 2e 0a 8f 20 4e 65 77 20 53 |rlooked... New S| 000009a0 57 49 20 61 64 64 65 64 20 2d 20 53 6c 69 64 69 |WI added - Slidi| 000009b0 6e 67 48 65 61 70 5f 49 6e 63 72 65 61 73 65 53 |ngHeap_IncreaseS| 000009c0 6c 6f 74 73 2e 20 20 20 54 68 69 73 20 61 6c 6c |lots. This all| 000009d0 6f 77 73 20 70 72 6f 67 72 61 6d 73 20 74 6f 20 |ows programs to | 000009e0 75 73 65 20 61 20 69 6e 64 65 74 65 72 6d 69 6e |use a indetermin| 000009f0 61 74 65 20 6e 75 6d 62 65 72 20 6f 66 20 62 6c |ate number of bl| 00000a00 6f 63 6b 73 2c 20 77 69 74 68 6f 75 74 20 68 61 |ocks, without ha| 00000a10 76 69 6e 67 20 74 6f 20 73 65 74 20 61 6e 20 75 |ving to set an u| 00000a20 70 70 65 72 20 6c 69 6d 69 74 20 61 74 20 74 68 |pper limit at th| 00000a30 65 20 74 69 6d 65 20 6f 66 20 69 6e 69 74 69 61 |e time of initia| 00000a40 6c 69 73 61 74 69 6f 6e 2e 0a 0a 56 65 72 73 69 |lisation...Versi| 00000a50 6f 6e 20 32 2e 31 31 20 28 31 36 20 44 65 63 20 |on 2.11 (16 Dec | 00000a60 32 30 30 32 29 0a 8f 20 20 41 20 66 65 77 20 6d |2002).. A few m| 00000a70 6f 72 65 20 53 55 42 53 20 6f 70 74 69 6d 69 73 |ore SUBS optimis| 00000a80 61 74 69 6f 6e 73 2e 0a |ations..| 00000a88
.