1 files changed, 232 insertions, 0 deletions

diff --git a/v4.0/src/DOS/UTIL.ASM b/v4.0/src/DOS/UTIL.ASM
new file mode 100644
index 0000000..3c9c516
--- /dev/null
+++ b/v4.0/src/DOS/UTIL.ASM
@@ -0,0 +1,232 @@
+;       SCCSID = @(#)util.asm   1.1 85/04/10
+TITLE   UTIL - Handle utilities
+NAME    UTIL
+;
+; Handle related utilities for MSDOS 2.X.
+;
+;   pJFNFromHandle  written
+;   SFFromHandle    written
+;   SFFromSFN       written
+;   JFNFree         written
+;   SFNFree         written
+;
+;   Modification history:
+;
+;       Created: MZ 1 April 1983
+;
+
+.xlist
+;
+; get the appropriate segment definitions
+;
+include dosseg.asm
+
+CODE    SEGMENT BYTE PUBLIC  'CODE'
+        ASSUME  SS:DOSGROUP,CS:DOSGROUP
+
+.xcref
+INCLUDE DOSSYM.INC
+INCLUDE DEVSYM.INC
+.cref
+.list
+.sall
+
+        I_need  CurrentPDB,WORD         ; current process data block location
+        I_need  SFT_Addr,DWORD          ; pointer to beginning of table
+        I_Need  PROC_ID,WORD            ; current process ID
+        I_Need  USER_ID,WORD            ; current user ID
+if debug
+        I_need  BugLev,WORD
+        I_need  BugTyp,WORD
+include bugtyp.asm
+endif
+
+BREAK   <pJFNFromHandle - return pointer to JFN table entry>
+
+;
+;   pJFNFromHandle - Given a handle, return the pointer to the JFN location
+;       in the user's data space
+;   Inputs:     BX - Handle
+;   Outputs:    Carry Set
+;                   AX has error code
+;               Carry reset
+;                   ES:DI point to the handle spot
+;   Registers modified:
+;               If no error, ES:DI, else AX,ES
+; NOTE:
+;   This routine is called from $CREATE_PROCESS_DATA_BLOCK which is called
+;       at DOSINIT time with SS NOT DOSGROUP
+procedure   pJFNFromHandle,NEAR
+        ASSUME  CS:DOSGROUP,DS:NOTHING,ES:NOTHING,SS:NOTHING
+        MOV     ES,[CurrentPDB]         ; get user process data block
+        CMP     BX,ES:[PDB_JFN_Length]  ; is handle greater than allocated
+        JB      JFNAdd                  ; no, get offset
+        fmt     TypAccess,LevSFN,<"$p: Illegal JFN %x\n">,<BX>
+        MOV     AL,error_invalid_handle ; appropriate error
+ReturnCarry:
+        STC                             ; signal error
+        return                          ; go back
+JFNAdd: LES     DI,ES:[PDB_JFN_Pointer] ; get pointer to beginning of table
+        ADD     DI,BX                   ; add in offset
+ReturnNoCarry:
+        CLC                             ; no holes
+        return                          ; bye!
+EndProc pJFNFromHandle
+
+BREAK <SFFromHandle - return pointer (or error) to SF entry from handle>
+
+;
+; SFFromHandle - Given a handle, get JFN and then index into SF table
+;
+;   Input:      BX has handle
+;   Output:     Carry Set
+;                   AX has error code
+;               Carry Reset
+;                   ES:DI has pointer to SF entry
+;   Registers modified: If error, AX,ES, else ES:DI
+; NOTE:
+;   This routine is called from $CREATE_PROCESS_DATA_BLOCK which is called
+;       at DOSINIT time with SS NOT DOSGROUP
+procedure   SFFromHandle,NEAR
+        ASSUME  CS:DOSGROUP,DS:NOTHING,ES:NOTHING,SS:NOTHING
+        CALL    pJFNFromHandle          ; get jfn pointer
+        retc                            ; return if error
+        CMP     BYTE PTR ES:[DI],-1     ; unused handle
+        JNZ     GetSF                   ; nope, suck out SF
+        fmt     TypAccess,LevSFN,<"$p: Illegal SFN $x:$x\n">,<ES,DI>
+        MOV     AL,error_invalid_handle ; appropriate error
+        jump    ReturnCarry             ; signal it
+GetSF:
+        SaveReg <BX>                    ; save handle
+        MOV     BL,BYTE PTR ES:[DI]     ; get SFN
+        XOR     BH,BH                   ; ignore upper half
+        CALL    SFFromSFN               ; get real sf spot
+        RestoreReg  <BX>                ; restore
+        return                          ; say goodbye
+EndProc SFFromHandle
+
+BREAK <SFFromSFN - index into SF table for SFN>
+
+;
+; SFFromSFN - index into SF tables for SFN.
+;
+;   Input:      BX has SF index
+;   Output:     ES:DI points to SF entry
+;   Registers modified: ES:DI, BX only
+; NOTE:
+;   This routine is called from SFFromHandle which is called
+;       at DOSINIT time with SS NOT DOSGROUP
+procedure   SFFromSFN,NEAR
+        ASSUME  CS:DOSGROUP,DS:NOTHING,ES:NOTHING,SS:NOTHING
+        LES     DI,[SFT_Addr]           ; get pointer to beginning of table
+ScanLoop:
+        CMP     BX,ES:[DI].SFCount      ; is handle in this table?
+        JB      GetOffset               ; yes, go grab it
+        SUB     BX,ES:[DI].SFCount
+        LES     DI,ES:[DI].SFLink       ; get next table segment
+        CMP     DI,-1                   ; end of tables?
+        JNZ     ScanLoop                ; no, try again
+        STC                             ; error...
+        JMP     SHORT Restore           ; go restore
+GetOffset:
+        SaveReg <AX>                    ; save AX
+        MOV     AX,SIZE SF_Entry        ; put it in a nice place
+        MUL     BL                      ; times size
+        ADD     DI,AX                   ; offset by size
+        RestoreReg  <AX>                ; get world back
+        ADD     DI,SFTable              ; offset into structure
+        CLC                             ; no holes
+Restore:
+        return                          ; bye!
+EndProc SFFromSFN
+
+BREAK <JFNFree - return a jfn pointer if one is free>
+
+;
+; JFNFree - scan through the JFN table and return a pointer to a free slot
+;
+;   Input:  None.
+;   Output: Carry Set
+;               AX has error code, BX,ES,DI garbage
+;           Carry Reset
+;               BX has new handle, ES:DI is pointer to JFN slot
+;   Registers modified: As above only.
+procedure   JFNFree,NEAR
+        ASSUME  CS:DOSGROUP,DS:NOTHING,ES:NOTHING,SS:DOSGROUP
+        XOR     BX,BX                   ; try starting low
+JFNScan:
+        CALL    pJFNFromHandle          ; get the appropriate handle
+        JC      JFNNone                 ; no more handles
+        CMP     BYTE PTR ES:[DI],-1     ; free?
+        JZ      JFNFound                ; yes, carry is clear
+        INC     BX                      ; no, next handle
+        JMP     JFNScan                 ; and try again
+JFNNone:
+        MOV     AL,error_too_many_open_files
+JFNFound:
+        return                          ; bye
+EndProc JFNFree
+
+BREAK <SFNFree - find a free SFN>
+
+;
+;   SFNFree - scan through the sf table looking for free entries
+;   Inputs:     none
+;   Outputs:    Carry Set - AX has error code, BX destroyed
+;               Carry Clear - BX has SFN
+;                   ES:DI - pointer to SFT
+;                   SFT_ref_count is set to 1
+;   Registers modified: none
+
+Procedure SFNFree,NEAR
+        ASSUME  CS:DOSGROUP,DS:NOTHING,ES:NOTHING,SS:DOSGROUP
+        XOR     BX,BX                   ; start at beginning
+SFNFreeLoop:
+        SaveReg <BX>                    ; Next call zaps BX
+        CALL    SFFromSFN               ; get the potential handle
+        RestoreReg  <BX>
+        JNC     SFNCheck                ; no carry, check to see if its free
+        MOV     AL,error_too_many_open_files    ; appropriate error
+        JMP     SFNDone
+SFNCheck:
+        CMP     ES:[DI.sf_Ref_Count],0  ; free?
+IF NOT DEBUG
+        JZ      SFNGot                  ; yep, got return him
+ELSE
+        JNZ     NoGot
+        JMP     SFNGot
+NoGot:
+ENDIF
+        CMP     ES:[DI.sf_ref_count],sf_busy
+        JNZ     SFNNext                 ; not marked busy...
+        fmt     TypAccess,LevSFN,<"$p: SFT $x:$x($x)is busy, owner $x:$x\n">,<ES,DI,BX,ES:[DI].sf_UID,ES:[DI].sf_pid>
+        SaveReg <BX>
+        MOV     BX,User_ID
+        CMP     ES:[DI.sf_UID],BX
+        JNZ     SFNNextP
+        MOV     BX,Proc_ID
+        CMP     ES:[DI.sf_PID],BX
+        JZ      SFNGotP
+SFNNextP:
+        fmt     TypAccess,LevSFN,<"$p: SFT unusable\n">
+        RestoreReg  <BX>
+SFNNext:
+        INC     BX                      ; no, try next sf number
+        JMP     SFNFreeLoop             ; and go until it fails
+SFNGot:
+        SaveReg <BX>
+SFNGotP:
+        CLC                             ; no error
+        fmt     TypAccess,LevSFN,<"$p: SFT $x:$x($x) marked busy\n">,<ES,DI,BX>
+        MOV     ES:[DI.sf_ref_count],sf_busy    ; make sure that this is allocated
+        MOV     BX,User_ID
+        MOV     ES:[DI.sf_UID],BX
+        MOV     BX,Proc_ID
+        MOV     ES:[DI.sf_PID],BX
+        RestoreReg  <BX>
+SFNDone:
+        return                          ; bye
+EndProc SFNFree
+
+CODE    ENDS
+END