1 files changed, 65 insertions, 0 deletions

diff --git a/v4.0/src/MAPPER/FREESEG.ASM b/v4.0/src/MAPPER/FREESEG.ASM
new file mode 100644
index 0000000..b3f2c1c
--- /dev/null
+++ b/v4.0/src/MAPPER/FREESEG.ASM
@@ -0,0 +1,65 @@
+;
+page 60,132
+;
+title CP/DOS  DosFreeSeg  mapper
+;
+dosxxx  segment byte public 'dos'
+        assume  cs:dosxxx,ds:nothing,es:nothing,ss:nothing
+;
+; ************************************************************************* *
+; *
+; *      MODULE: DosFreeSeg
+; *
+; *      FILE NAME: dos023.asm
+; *
+; *      FUNCTION: This module deallocates a segment
+; *
+; *
+; *      CALLING SEQUENCE:
+; *
+; *             push    selector        ; selector of the segment
+; *             call    dosfreeseg
+; *
+; *      RETURN SEQUENCE:
+; *
+; *      MODULES CALLED:  DOS int 21h, ah=49h
+; *
+; *************************************************************************
+
+        public  dosfreeseg
+        .sall
+        .xlist
+        include macros.inc
+        .list
+
+invalid_selector equ 0006h
+
+
+str     struc
+Old_bp   dw      ?
+Return   dd      ?
+Selector dw      ?         ; selector of the segment to be freed
+str     ends
+
+dosfreeseg proc   far
+        Enter   dosfreeseg              ; push registers
+
+        mov     es,[bp].selector        ; get selector in es
+
+        mov     ah,49h
+        int     21h                     ; free memory segment
+        jc      error                   ; jump if error
+
+        sub     ax,ax                   ; zero return code
+        jmp     exit                    ; go to exit
+
+error:  mov     ax,invalid_selector     ; put in error code
+
+exit:   Mexit                           ; pop registers
+        ret     size str - 6            ; return
+
+dosfreeseg endp
+
+dosxxx  ends
+
+        end