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Digital Research
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MPM OPERATING SYSTEMS/MPM-86/MPM-86 2.0 SOURCES/02/CPMMEM.MEM
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176
MPM OPERATING SYSTEMS/MPM-86/MPM-86 2.0 SOURCES/02/CPMMEM.MEM
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;*****************************************************
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;*
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;* MEM Entry Points
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;*
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;*****************************************************
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; Format of Memory Control Block used
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; in CP/M-86 Memory Calls (53 - 58)
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;
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; +-----------+-----------+-----+
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; MCB | Base | Length | ext |
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; +-----------+-----------+-----+
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;
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mcb_base equ word ptr 0
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mcb_length equ word ptr mcb_base + word
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mcb_ext equ byte ptr mcb_length + word
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mcblen equ mcb_ext + byte
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;============ =====================
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maxmem_entry: ; 53 - Get Max Memory
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;============ =====================
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; input: DX = address of MCB in u_wrkseg
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; output: BX = 0ffffh if failure
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; 0h if success
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; CX = Error Code
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; mcb_ext = 0 if no additional mem
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; 1 if more available
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mov si,dx
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push ds ! mov ds,u_wrkseg
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mov dx,mcb_length[si] ! pop ds
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sub ax,ax ! mov bx,ax
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call getmemory ! jcxz mm_gm
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mov bx,0ffffh ! ret
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mm_gm: push ds ! mov ds,u_wrkseg
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mov mcb_length[si],dx
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mov mcb_base[si],ax
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mov mcb_ext[si],1
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pop ds ! sub bx,bx ! ret
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;============
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absmax_entry: ; 54 - Get Abs Max Mem
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;============
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; Allocate the largest absolute memory region which
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; is less than or equal mcb_length
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; input: DX = address of MCB in u_wrkseg
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; output: BX = 0ffffh if failure
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; 0h if success
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; CX = Error Code
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mov si,dx
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push ds ! mov ds,u_wrkseg
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mov ax,mcb_base[si]
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mov dx,mcb_length[si] ! pop ds
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sub bx,bx
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call getmemory ! jcxz am_gm
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mov bx,0ffffh ! ret
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am_gm: push ds ! mov ds,u_wrkseg
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mov mcb_length[si],dx
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mov mcb_base[si],ax
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pop ds ! sub bx,bx ! ret
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;==============
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cpmalloc_entry: ; 55 - Alloc Mem
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;==============
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; Allocate a memory region which is equal to mcb_length
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;
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; input: DX = address of MCB in u_wrkseg
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; output: BX = 0ffffh if failure
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; 0h if success
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; CX = Error Code
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mov si,dx
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push ds ! mov ds,u_wrkseg
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sub ax,ax ! mov bx,mcb_length[si]
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mov dx,bx ! pop ds
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call getmemory ! jcxz ca_gm
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mov bx,0ffffh ! ret
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ca_gm: push ds ! mov ds,u_wrkseg
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mov mcb_length[si],dx
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mov mcb_base[si],ax
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pop ds ! sub bx,bx ! ret
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;=============
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cpmabsa_entry: ; 56 - Alloc Abs Mem
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;=============
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; Allocate an absolut memory region which is
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; equal to mcb_length
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;
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; input: DX = address of MCB in u_wrkseg
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; output: BX = 0ffffh if failure
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; 0h if success
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; CX = Error Code
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mov si,dx
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push ds ! mov ds,u_wrkseg
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mov ax,mcb_base[si]
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mov bx,mcb_length[si]
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mov dx,bx ! pop ds
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call getmemory ! jcxz caa_gm
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mov bx,0ffffh ! ret
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caa_gm: push ds ! mov ds,u_wrkseg
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mov mcb_length[si],dx
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mov mcb_base[si],ax
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pop ds ! sub bx,bx ! ret
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getmemory:
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;---------
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; input: AX = start
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; BX = min
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; DX = max
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; output: AX = start
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; DX = length
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; CX = error code
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; preserve SI
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push si
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sub cx,cx ! push cx ! push cx ! push dx ! push bx
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push ax ! mov dx,sp
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push ds ! mov cx,ss ! mov ds,cx
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mov cx,f_malloc ! call mpmif
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pop ds ! pop ax ! pop dx ! pop bx ! pop bx ! pop bx
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pop si ! ret
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;=============
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cpmfree_entry: ; 57 - Free Mem
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;=============
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; Free memory as specified in MCB
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; input: DX = offset of MCB in u_wrkseg
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; mcb_ext = 0ffh = free all but load mem
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; else as specified by mcb_base.
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; mcb_base = seg addr of memory segment
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; to free. IF in middle of
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; existing segment then just free
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; the end of the segment.
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push ds ! mov ds,u_wrkseg
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mov si,dx
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mov al,mcb_ext[si]
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mov dx,mcb_base[si] ! pop ds
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cmp al,0ffh ! jne free_memory
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cpmf_root: mov bx,rlr
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add bx,p_mem-ms_link
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cpmf_next: mov si,ms_link[bx]
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cmp si,0 ! jne try_seg
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sub bx,bx ! mov cx,bx ! ret
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try_seg: and ms_flags[si],mf_load ! jz free_seg
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mov bx,si ! jmps cpmf_next
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free_seg: mov dx,ms_start[si]
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push si ! call free_memory ! pop si
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jcxz cpmf_root
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jmps cpmf_next
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free_memory:
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;-----------
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; input: DX = start
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; output: BX = 0,0ffffh (success,fail)
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; CX = Error Code
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push ds ! push ss ! pop ds
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sub cx,cx ! push cx ! push dx
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mov dx,sp
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mov cx,f_memfree ! call mpmif
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pop dx ! pop dx ! pop ds
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ret
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;=============
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freeall_entry: ; 58 - Free All Mem
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;=============
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mov cx,f_terminate ! sub dx,dx
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jmp mpmif
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