From c68d73faa6525837c27b6b8404168a9e5dcf761d Mon Sep 17 00:00:00 2001
From: Mario Fetka <mario.fetka@gmail.com>
Date: Sat, 23 May 2026 16:59:44 +0200
Subject: [PATCH] tests

---
 kern_wasm.asm | 55 ++++++++++++++++++++++++---------------------------
 nwtests.c     | 28 ++++++++++++++------------
 2 files changed, 41 insertions(+), 42 deletions(-)

diff --git a/kern_wasm.asm b/kern_wasm.asm
index 61fbe70..abfc602 100644
--- a/kern_wasm.asm
+++ b/kern_wasm.asm
@@ -6,7 +6,7 @@
 ; Keep kern.asm as the historical TASM source and use this file for the
 ; reproducible Open Watcom build.
 
-.386
+.286
 .model large
 
 .data
@@ -290,21 +290,19 @@ _Net_Call_VLM_Raw endp
 
 ; int C32_LoadNios_Probe(UI axfunc, void *outbuf)
 ;
-; Probe the Client32/NIOS INT 2F entry used by DeveloperNet dninit.asm:
-;   AX = axfunc, normally D8C1h
-;   INT 2Fh
-;   AX = 0000 on success
-;   ESI and ECX contain Client32/NIOS function pointers/data
+; 16-bit-safe Client32/NIOS probe.
+; Calls INT 2F AX=D8C1 like DeveloperNet LoadNiosFunctions,
+; but stores only 16-bit visible registers so kern.obj stays 16-bit.
 ;
-; outbuf layout, little endian:
-;   +00 word AX after int 2F
-;   +02 dword ESI after int 2F
-;   +06 dword ECX after int 2F
-;   +0A word BX
-;   +0C word CX low
-;   +0E word DX
-;   +10 word SI low
-;   +12 word DI low
+; outbuf:
+;   +00 AX
+;   +02 BX
+;   +04 CX
+;   +06 DX
+;   +08 SI
+;   +0A DI
+;   +0C DS
+;   +0E ES
 _C32_LoadNios_Probe proc far
         push    bp
         mov     bp, sp
@@ -314,26 +312,25 @@ _C32_LoadNios_Probe proc far
         push    si
         push    di
 
-        xor     ecx, ecx
-        xor     esi, esi
-        xor     ebx, ebx
-        xor     edx, edx
-        xor     edi, edi
-
         mov     ax, [bp+6]
         int     2Fh
 
+        push    ds
+        push    ax
         les     di, dword ptr [bp+8]
 
+        pop     ax
         mov     es:[di+0], ax
-        mov     dword ptr es:[di+2], esi
-        mov     dword ptr es:[di+6], ecx
-        mov     es:[di+10], bx
-        mov     es:[di+12], cx
-        mov     es:[di+14], dx
-        mov     es:[di+16], si
-        ; DI currently points at outbuf, so store caller-visible DI is not useful.
-        mov     word ptr es:[di+18], 0
+        mov     es:[di+2], bx
+        mov     es:[di+4], cx
+        mov     es:[di+6], dx
+        mov     es:[di+8], si
+        ; store caller-visible DI is lost because DI now points to outbuf
+        mov     word ptr es:[di+10], 0
+        pop     ax
+        mov     es:[di+12], ax
+        mov     ax, es
+        mov     es:[di+14], ax
 
         pop     di
         pop     si
diff --git a/nwtests.c b/nwtests.c
index ce68855..fa12b7c 100644
--- a/nwtests.c
+++ b/nwtests.c
@@ -1147,33 +1147,35 @@ static int tests_c32type(void)
   uint8 out[32];
   int rc;
   uint16 ax;
-  uint32 esi;
-  uint32 ecx;
   uint16 bx;
   uint16 cx;
   uint16 dx;
   uint16 si;
+  uint16 di;
+  uint16 dsreg;
+  uint16 esreg;
 
   memset(out, 0, sizeof(out));
 
-  fprintf(stdout, "TEST Client32/NIOS probe\n");
+  fprintf(stdout, "TEST Client32/NIOS probe 16-bit safe\n");
   fprintf(stdout, "Call INT 2F AX=D8C1 like DeveloperNet dninit.asm\n\n");
 
   rc = C32_LoadNios_Probe(0xD8C1, out);
 
-  ax  = tests_get_word_lh(out + 0);
-  esi = tests_get_dword_lh2(out + 2);
-  ecx = tests_get_dword_lh2(out + 6);
-  bx  = tests_get_word_lh(out + 10);
-  cx  = tests_get_word_lh(out + 12);
-  dx  = tests_get_word_lh(out + 14);
-  si  = tests_get_word_lh(out + 16);
+  ax    = tests_get_word_lh(out + 0);
+  bx    = tests_get_word_lh(out + 2);
+  cx    = tests_get_word_lh(out + 4);
+  dx    = tests_get_word_lh(out + 6);
+  si    = tests_get_word_lh(out + 8);
+  di    = tests_get_word_lh(out + 10);
+  dsreg = tests_get_word_lh(out + 12);
+  esreg = tests_get_word_lh(out + 14);
 
   fprintf(stdout, "C32 probe rc=%04X\n", rc);
   fprintf(stdout, "INT2F D8C1 result AX=%04X\n", ax);
-  fprintf(stdout, "ESI=%08lX ECX=%08lX\n", esi, ecx);
-  fprintf(stdout, "BX=%04X CX=%04X DX=%04X SI=%04X\n", bx, cx, dx, si);
-  tests_dump_bytes("RAW:", out, 20);
+  fprintf(stdout, "BX=%04X CX=%04X DX=%04X SI=%04X DI=%04X\n", bx, cx, dx, si, di);
+  fprintf(stdout, "DS=%04X ES=%04X\n", dsreg, esreg);
+  tests_dump_bytes("RAW:", out, 16);
 
   if (ax == 0) {
     fprintf(stdout, "\nClient32/NIOS entry appears present.\n");