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--- calling_20internal_20routines_20from_20assembler_20code [2018/03/31 13:19] – external edit 127.0.0.1
+++ calling_20internal_20routines_20from_20assembler_20code [2024/01/05 00:22] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
 =====Calling internal routines from assembler code=====
-//by Richard Russell, January 2016//\\ \\  A small selection of subroutines, internal to the BB4W interpreter, is exposed to the assembly language programmer so that they may be called from his own assembler code. These are grouped into two sets; the most commonly needed subroutines are callable by **name** and the less commonly needed ones by a **jump table**. The first set is as follows (documented also in the main BB4W Help manual):\\ \\
+//by Richard Russell, January 2016//\\ \\  A small selection of subroutines, internal to the BASIC interpreter, is exposed to the assembly language programmer so that they may be called from his own assembler code. These are grouped into two sets; the most commonly needed subroutines are callable by **name** and the less commonly needed ones by a **jump table**. The first set is as follows (documented also in the main Help manual):\\
   CALL "osbget" ; Read byte from file to AL, EBX contains channel number
   CALL "osbput" ; Write byte from AL to file, EBX contains channel number
@@ Line 22: / Line 22: @@
   CALL "csenter"; Enter critical section (@memhdc% settings may change)
   CALL "csleave"; Leave critical section (@memhdc% may not be changed)
-\\  The second set is as follows (//BBC BASIC for Windows// v6.00a or later only):\\ \\
+The second set is as follows (//BBC BASIC for Windows// v6.00a or later and //BBC BASIC for SDL 2.0// only):
   CALL @fn%(0)  ; Load numeric (al=type, ebp=varptr, returns ebx,ecx,edx)
   CALL @fn%(1)  ; Load string (al=type, ebp=varptr, returns len=ecx, addr=edx)
@@ Line 41: / Line 43: @@
   CALL @fn%(16) ; EXP() function; calculate e raised to the power of (bx,ecx,edx)
   JMP  @fn%(17) ; Return to BASIC (jmp rather than call), esi addresses statement
-  CALL @fn%(18) ; Queue event (as in SYS @fn%(18), msg%, wparam%, lparam%)
+  SYS  @fn%(18) ; Queue an event: SYS @fn%(18), handler%, msg%, wparam%, lparam%
+Extensions in //BBC BASIC for SDL 2.0// only:
+  SYS @fn%(19)  ; Return a pointer to the current bitmap font: SYS @fn%(19) TO font%%
+  SYS @fn%(20)  ; Set the pointer to the current bitmap font: SYS @fn%(20), font%%
+  SYS @fn%(21)  ; Redefine a character: SYS @fn%(21), @memhdc%, char%, addr%%, w%, h%