new approach for dos port

2026-10-08 13:46:16 +03:00
parent dc594e5e82
commit b92458862e
6 changed files with 190 additions and 119 deletions
@@ -0,0 +1,47 @@
+.section .data
+    .align 4
+# The DPMI Register Structure (50 bytes total)
+# This holds the register states injected into Real Mode.
+dpmi_regs:
+    .long 0         # edi  (offset 0)
+    .long 0         # esi  (offset 4)
+    .long 0         # ebp  (offset 8)
+    .long 0         # esp / reserved (offset 12)
+    .long 0         # ebx  (offset 16)
+    .long 0         # edx  (offset 20)
+    .long 0         # ecx  (offset 24)
+dpmi_eax:
+    .long 0         # eax  (offset 28)
+    .short 0        # flags(offset 32)
+    .short 0        # es   (offset 34)
+    .short 0        # ds   (offset 36)
+    .short 0        # fs   (offset 38)
+    .short 0        # gs   (offset 40)
+    .short 0        # ip   (offset 42)
+    .short 0        # cs   (offset 44)
+    .short 0        # sp   (offset 46)
+    .short 0        # ss   (offset 48)
+
+.section .text
+.global _start
+
+_start:
+    call plr_display_dos_main
+
+    # 1. Set up the Real-Mode registers inside the DPMI structure
+    # AH = 4Ch (DOS Exit Function), AL = 00h (Return Code 0)
+    movl $0x00004C00, dpmi_eax
+
+    # 2. Call DPMI Simulate Real Mode Interrupt
+    movw $0x0300, %ax    # DPMI Function: Simulate Real Mode Interrupt
+    movb $0x21, %bl      # Interrupt number to trigger (INT 21h)
+    movb $0x00, %bh      # Flags (Must be 0)
+    movw $0x0000, %cx    # Number of words to copy to RM stack (0)
+    
+    # ES:EDI points to our DPMI register block. 
+    # In WDOSX flat model, %es already targets the flat data descriptor.
+    movl $dpmi_regs, %edi
+    
+    int $0x31            # Trigger DPMI host to execute the RM interrupt
+
+    # --- Execution halts here as DOS terminates the program ---