Started to add text output functions

git-svn-id: svn://svn.cc65.org/cc65/trunk@1427 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/tgi/tgi_textsize.s

@@ -0,0 +1,73 @@
+;                
+; Ullrich von Bassewitz, 22.06.2002
+;
+
+
+        .include        "tgi-kernel.inc"
+
+        .import         _strlen, pushax, tosumulax
+        .export         _tgi_textwidth
+        .export         _tgi_textheight
+
+;-----------------------------------------------------------------------------
+; unsigned __fastcall__ tgi_textwidth (const char* s);
+; /* Calculate the width of the text in pixels according to the current text
+;  * style.
+;  */
+
+
+_tgi_textwidth:
+        ldy     _tgi_textdir            ; Get text direction
+        bne     height
+
+; Result is
+;
+;       strlen (s) * tgi_textmagx * tgi_fontsizex
+;
+; Since we don't expect textmagx to have large values, we do the multiplication
+; by looping.
+
+width:  jsr     _strlen
+        jsr     pushax
+
+        lda     #0
+        tax
+        ldy     _tgi_textmagx
+@L1:    clc
+        adc     _tgi_fontsizex
+        bcc     @L2
+        inx
+@L2:    dey
+        bne     @L1
+
+        jmp     tosumulax               ; Result * strlen (s)
+
+;-----------------------------------------------------------------------------
+; unsigned __fastcall__ tgi_textheight (const char* s);
+; /* Calculate the height of the text in pixels according to the current text
+;  * style.
+;  */
+
+_tgi_textheight:
+        ldy     _tgi_textdir            ; Get text direction
+        bne     width                   ; Jump if vertical
+
+; Result is
+;
+;       tgi_textmagy * tgi_fontsizey
+;
+; Since we don't expect textmagx to have large values, we do the multiplication
+; by looping.
+
+height: lda     #0
+        tax
+        ldy     _tgi_textmagy
+@L1:    clc
+        adc     _tgi_fontsizey
+        bcc     @L2
+        inx
+@L2:    dey
+        bne     @L1
+        rts
+
+