| 1,7 → 1,7 |
|---|
| ; |
| ; rmod - resident module of the SvarCOM command interpreter (NASM code) |
| ; |
| ; Copyright (C) 2021-2022 Mateusz Viste |
| ; Copyright (C) 2021-2024 Mateusz Viste |
| ; MIT license |
| ; |
| ; this is installed in memory by the transient part of SvarCOM. it has only |
| 65,11 → 65,15 |
|---|
| ; MUST contain the 1st char of |
| ; REDIR_INFIL! |
| |
| EXEC_LH: db 0 ; +271h EXECPROG to be loaded high? |
| ORIG_UMBLINKSTATE: db 0 ; +272h |
| ORIG_ALLOCSTRAT: db 0 ; +273h |
| |
| ; CTRL+BREAK (int 23h) handler |
| ; According to the TechHelp! Manual: "If you want to abort (exit to the parent |
| ; process), then set the carry flag and return via a FAR RET. This causes DOS |
| ; to perform normal cleanup and exit to the parent." (otherwise use iret) |
| BREAK_HANDLER: ; +271h |
| BREAK_HANDLER: ; +274h |
| stc |
| retf |
| |
| 78,7 → 82,7 |
|---|
| xor ax, ax |
| iret |
| |
| skipsig: ; +276h |
| skipsig: ; +279h |
| |
| ; set up CS=DS=SS and point SP to my private stack buffer |
| mov ax, cs |
| 113,6 → 117,30 |
|---|
| ;mov bx, cs |
| ;int 0x21 |
| |
| |
| ; LOADHIGH? |
| cmp [EXEC_LH], byte 0 |
| je NO_LOADHIGH |
| ; SAVE CURRENT UMB LINK STATE |
| mov ax, 0x5802 ; GET UMB LINK STATE |
| int 0x21 |
| mov [ORIG_UMBLINKSTATE], al |
| ; SAVE CURRENT ALLOCATION STRATEGY |
| mov ax, 0x5800 |
| int 0x21 |
| mov [ORIG_ALLOCSTRAT], al |
| |
| ; LOADHIGH: link in the UMB memory chain for enabling high-memory allocation |
| ; (and save initial status on stack) |
| mov ax, 0x5803 ; SET UMB LINK STATE */ |
| mov bx, 1 |
| int 0x21 |
| ; set strategy to 'last fit, try high then low memory' |
| mov ax, 0x5801 |
| mov bx, 0x0082 |
| int 0x21 |
| NO_LOADHIGH: |
| |
| ; exec an application preset (by SvarCOM) in the ExecParamRec |
| mov ax, 0x4B00 ; DOS 2+ - load & execute program |
| mov dx, EXECPROG ; DS:DX - ASCIZ program name (preset at PSP[already) |
| 120,8 → 148,26 |
|---|
| int 0x21 |
| mov [cs:EXECPROG], byte 0 ; do not run app again (+DS might have been changed) |
| |
| jmp short skipsig ; enforce valid ds/ss/etc (can be lost after int 21,4b) |
| ; go to start if nothing else to do (this will enforce valid ds/ss/etc) |
| cmp [cs:EXEC_LH], byte 0 |
| je skipsig |
| |
| ; restore UMB link state and alloc strategy to original values (but make sure |
| ; to base it on CS since DS might have been trashed by the program) |
| mov ax, 0x5803 |
| xor bx, bx |
| mov bl, [cs:ORIG_UMBLINKSTATE] |
| int 0x21 |
| ; restore original memory allocation strategy |
| mov ax, 0x5801 |
| mov bl, [cs:ORIG_ALLOCSTRAT] |
| int 0x21 |
| ; turn off the LH flag |
| mov [cs:EXEC_LH], byte 0 |
| |
| |
| jmp skipsig ; enforce valid ds/ss/etc (can be lost after int 21,4b) |
| |
| EXEC_COMMAND_COM: |
| |
| ; collect the exit code of previous application |
| 136,6 → 182,9 |
|---|
| cld ; stosb must move forward |
| rep stosb ; repeat cx times |
| |
| ; zero out the LH flag |
| mov [EXEC_LH], byte 0 |
| |
| ; preset the default COMSPEC pointer to ES:DX (ES is already set to DS) |
| mov dx, COMSPECBOOT |
| |