diff --git a/curs/chap-05-ihs/io.mac b/curs/chap-05-ihs/io.mac
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+;;; macro to use printf with 32bit parameters:
+;;; - 1st parameter MUST be an immediate in backquotes `EAX=%d ECX=%x \n\x0`
+;;;     escape \n and \x0 only work with backquotes
+;;; - rest of parameters MUST be 32bit
+;;; - gen purpose and flags are preserved
+;;; - stack is cleaned
+%macro PRINTF32 1-*
+    pushf
+    pushad
+    jmp     %%endstr
+%%str:       db      %1
+%%endstr:
+%rep  %0 - 1
+%rotate -1
+    push    dword %1
+%endrep
+    push %%str
+    call printf
+    add esp, 4*%0
+    popad
+    popf
+%endmacro