Implemented RFE #1702376

[fw/sdcc] / device / lib / z80 / mulchar.s

diff --git a/device/lib/z80/mulchar.s b/device/lib/z80/mulchar.s
new file mode 100644 (file)
index 0000000..7217dd8
--- /dev/null
+++ b/device/lib/z80/mulchar.s
@@ -0,0 +1,73 @@
+        .area   _CODE
+
+; This multiplication routine is similar to the one
+; from Rodnay Zaks, "Programming the Z80".
+
+; Now replaced by a builtin for code generation, but
+; still called from some asm files in this directory.
+__muluchar_rrx_s::
+        ld      hl, #2+1
+        add     hl, sp
+        ld      e, (hl)
+        dec     hl
+        ld      h, (hl)
+        ld      l, #0
+        ld      d, l
+        ld      b, #8
+muluchar_rrx_s_loop:
+        add     hl, hl
+        jr      nc, muluchar_rrx_s_noadd
+        add     hl, de
+muluchar_rrx_s_noadd:
+        djnz    muluchar_rrx_s_loop
+        ret
+
+; operands have different sign
+
+__mulsuchar_rrx_s::
+        ld      hl,#2+1
+        add     hl,sp
+
+        ld      e,(hl)
+        dec     hl
+        ld      c,(hl)
+        ld      b, #0
+        jr      signexte
+
+__muluschar_rrx_s::
+        ld      hl,#2+1
+        add     hl,sp
+
+        ld      c,(hl)
+        ld      b, #0
+        dec     hl
+        ld      e,(hl)
+        jr      signexte
+
+;; Originally from GBDK by Pascal Felber.
+
+__mulschar_rrx_s::
+        ld      hl,#2+1
+        add     hl,sp
+
+        ld      e,(hl)
+        dec     hl
+        ld      l,(hl)
+
+        ;; Fall through
+__mulschar_rrx_hds::
+        ;; Need to sign extend before going in.
+        ld      c,l
+
+        ld      a,l
+        rla
+        sbc     a,a
+        ld      b,a
+signexte:
+        ld      a,e
+        rla
+        sbc     a,a
+        ld      d,a
+
+        jp      __mul16
+