Initall commit

fasmw172/SOURCE/DOS/DPMI.INC

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+
+; flat assembler interface for DOS
+; Copyright (c) 1999-2017, Tomasz Grysztar.
+; All rights reserved.
+
+init_dpmi_memory:
+	mov	ax,500h 		; get free memory information
+	mov	edi,[buffer_address]
+	int	31h
+	mov	ebx,[edi]
+    allocate_dpmi_memory:
+	mov	edx,[memory_setting]
+	shl	edx,10
+	jz	dpmi_memory_size_ok
+	cmp	ebx,edx
+	jbe	dpmi_memory_size_ok
+	mov	ebx,edx
+    dpmi_memory_size_ok:
+	mov	[memory_end],ebx
+	mov	ecx,ebx
+	shr	ebx,16
+	mov	ax,501h
+	int	31h
+	jnc	dpmi_memory_ok
+	mov	ebx,[memory_end]
+	shr	ebx,1
+	cmp	ebx,4000h
+	jb	out_of_memory
+	jmp	allocate_dpmi_memory
+    dpmi_memory_ok:
+	shl	ebx,16
+	mov	bx,cx
+	sub	ebx,[program_base]
+	jc	out_of_memory
+	mov	[memory_start],ebx
+	add	[memory_end],ebx
+	mov	ax,100h 		; get free conventional memory size
+	mov	bx,-1
+	int	31h
+	movzx	ecx,bx
+	shl	ecx,4
+	jecxz	no_conventional_memory
+	mov	ax,100h 		; allocate all conventional memory
+	int	31h
+	movzx	edi,ax
+	shl	edi,4
+	sub	edi,[program_base]
+	jc	no_conventional_memory
+	mov	[additional_memory],edi
+	mov	[additional_memory_end],edi
+	add	[additional_memory_end],ecx
+	mov	eax,[memory_end]
+	sub	eax,[memory_start]
+	shr	eax,2
+	cmp	eax,ecx
+	ja	no_conventional_memory
+	ret
+    no_conventional_memory:
+	mov	eax,[memory_end]
+	mov	ebx,[memory_start]
+	sub	eax,ebx
+	shr	eax,2
+	mov	[additional_memory],ebx
+	add	ebx,eax
+	mov	[additional_memory_end],ebx
+	mov	[memory_start],ebx
+	ret
+
+dpmi_dos_int:
+	mov	[real_mode_segment],main
+    simulate_real_mode:
+	push	0			; SS:SP (DPMI will allocate stack)
+	push	0			; CS:IP (ignored)
+	push	0
+	push	[real_mode_segment]	; DS
+	push	[real_mode_segment]	; ES
+	stc
+	pushfw
+	push	eax
+	push	ecx
+	push	edx
+	push	ebx
+	push	0
+	push	ebp
+	push	esi
+	push	edi
+	mov	ax,300h
+	mov	bx,21h
+	xor	cx,cx
+	mov	edi,esp
+	push	es ss
+	pop	es
+	int	31h
+	pop	es
+	mov	edi,[esp]
+	mov	esi,[esp+4]
+	mov	ebp,[esp+8]
+	mov	ebx,[esp+10h]
+	mov	edx,[esp+14h]
+	mov	ecx,[esp+18h]
+	mov	ah,[esp+20h]
+	add	esp,32h
+	sahf
+	mov	eax,[esp-32h+1Ch]
+	ret
+dpmi_dos_int_with_buffer:
+	mov	[real_mode_segment],buffer
+	jmp	simulate_real_mode