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CauseWay - ExecOverlay - LOAD AND OPTIONALLY EXECUTE APP CODE

AX = FF24h
EBX = flags
bit 0:
Don't execute (overlay only)
bit 1:
Don't preserve relocation information.
ES:EDX -> filename (see also #03163).
FS:ESI -> commandline (ESI = 00000000h if no commandline).
GS:EDI -> name (CW's /o option)

Return:
CF clear if successful
---EBX bit 0 set---
CX:EDX = program entry point (CS:EIP)
SI = segment of PSP
---EBX bit 1 set---
BX:EAX = initial SS:ESP
EDI high word = base segment
EDI low word = number of segments
EBP = start of segment definitions
CF set on error
AX = error code
0001h DOS file access error
0002h not a CuaseWay 3P file
0003h not enough memory

See Also: AX=FF2Ah - INT 21/AH=4Bh

Format of CauseWay executable:

Offset  Size    Description     (Table 03163)
00h  2 BYTEs   signature "3P"
02h    DWORD   size of header data in bytes
06h    DWORD   size of EXE image data in bytes
0Ah    DWORD   number of bytes of program memory required
0Eh    WORD    number of segment definitions (see #03165)
10h    DWORD   number of relocation table entries
14h    DWORD   offset of program entry point
18h    WORD    segment list entry number for entry point's CS
1Ah    DWORD   initial ESP
1Eh    WORD    segment list entry number for initial SS
20h    DWORD   control flags (see #03164)
24h    DWORD   automatic stack size in bytes if ESP entry = 00000000h
28h    BYTE    length of name (name follows program image)
29h 23 BYTEs   reserved

See Also: #01594 - #01609 at INT 21/AH=4Bh

Bitfields for CauseWay executable control flags:

Bit(s)  Description     (Table 03164)
0      16-bit interrupt stack frame
7      descriptor table type (0 = GDT, 1 = LDT)
14     16-bit default data size
31     compressed EXE image

Note: Bits 0 and 14 should always be equal

See Also: #03163

Format of CauseWay segment definition [array]:

Offset  Size    Description     (Table 03165)
00h    DWORD   start offset within program image
04h    DWORD   length and type
bits 0-19:
Length
bit 20:
Granularity (if set, length is in 4K pages)
bits 21-24:
Type
0000 code
0001 read/write data
0010 stack
0011 read-only data
bit 25:
Force segment descriptor's D bit to 0
bit 26:
Force segmetn descriptor's D bit to 1

See Also: #03163

Category: DOS Extenders - Int 31h - C

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