cc65/libsrc/runtime/umul8x8r16.s

;
; Ullrich von Bassewitz, 2010-11-02
;
; CC65 runtime: 8x8 => 16 unsigned multiplication
;

        .export         umul8x8r16, umul8x8r16m
        .importzp       ptr1, ptr3


;---------------------------------------------------------------------------
; 8x8 => 16 unsigned multiplication routine.
;
;   LHS            RHS          result      result in also
; -------------------------------------------------------------
;   .A (ptr3-low)  ptr1-low     .XA             ptr1
;

umul8x8r16:
        sta     ptr3
umul8x8r16m:
        lda     #0              ; Clear byte 1
        ldy     #8              ; Number of bits
        lsr     ptr1            ; Get first bit of RHS into carry
@L0:    bcc     @L1
        clc
        adc     ptr3
@L1:    ror
        ror     ptr1
        dey
        bne     @L0
        tax
        stx     ptr1+1          ; Result in .XA and ptr1
        lda     ptr1            ; Load the result
        rts                     ; Done
Added separate 8x8=>16 multiplication routine as start of the multiplication and division stuff cleanup. git-svn-id: svn://svn.cc65.org/cc65/trunk@4431 b7a2c559-68d2-44c3-8de9-860c34a00d81 2009-11-02 22:28:02 +00:00			`;`
			`; Ullrich von Bassewitz, 2010-11-02`
			`;`
Fixed the comments to say where the actual Left-Hand Side and Right-Hand Side are put. A description of positions [left, right] is appropriate more for C code than for Assembly code. (A description of timing [first argument, second argument] is more appropriate for the way that Assembly code is written.) 2014-05-11 14:43:06 +00:00			`; CC65 runtime: 8x8 => 16 unsigned multiplication`
Added separate 8x8=>16 multiplication routine as start of the multiplication and division stuff cleanup. git-svn-id: svn://svn.cc65.org/cc65/trunk@4431 b7a2c559-68d2-44c3-8de9-860c34a00d81 2009-11-02 22:28:02 +00:00			`;`

Removed (pretty inconsistently used) tab chars from source code base. 2013-05-09 11:56:54 +00:00			`.export umul8x8r16, umul8x8r16m`
			`.importzp ptr1, ptr3`
Added separate 8x8=>16 multiplication routine as start of the multiplication and division stuff cleanup. git-svn-id: svn://svn.cc65.org/cc65/trunk@4431 b7a2c559-68d2-44c3-8de9-860c34a00d81 2009-11-02 22:28:02 +00:00

			`;---------------------------------------------------------------------------`
Fixed the comments to say where the actual Left-Hand Side and Right-Hand Side are put. A description of positions [left, right] is appropriate more for C code than for Assembly code. (A description of timing [first argument, second argument] is more appropriate for the way that Assembly code is written.) 2014-05-11 14:43:06 +00:00			`; 8x8 => 16 unsigned multiplication routine.`
Added separate 8x8=>16 multiplication routine as start of the multiplication and division stuff cleanup. git-svn-id: svn://svn.cc65.org/cc65/trunk@4431 b7a2c559-68d2-44c3-8de9-860c34a00d81 2009-11-02 22:28:02 +00:00			`;`
Fixed the comments to say where the actual Left-Hand Side and Right-Hand Side are put. A description of positions [left, right] is appropriate more for C code than for Assembly code. (A description of timing [first argument, second argument] is more appropriate for the way that Assembly code is written.) 2014-05-11 14:43:06 +00:00			`; LHS RHS result result in also`
Added separate 8x8=>16 multiplication routine as start of the multiplication and division stuff cleanup. git-svn-id: svn://svn.cc65.org/cc65/trunk@4431 b7a2c559-68d2-44c3-8de9-860c34a00d81 2009-11-02 22:28:02 +00:00			`; -------------------------------------------------------------`
Fixed the comments to say where the actual Left-Hand Side and Right-Hand Side are put. A description of positions [left, right] is appropriate more for C code than for Assembly code. (A description of timing [first argument, second argument] is more appropriate for the way that Assembly code is written.) 2014-05-11 14:43:06 +00:00			`; .A (ptr3-low) ptr1-low .XA ptr1`
Added separate 8x8=>16 multiplication routine as start of the multiplication and division stuff cleanup. git-svn-id: svn://svn.cc65.org/cc65/trunk@4431 b7a2c559-68d2-44c3-8de9-860c34a00d81 2009-11-02 22:28:02 +00:00			`;`

			`umul8x8r16:`
Rename the 8x8 multiplication using the same scheme as for the 16x16 multiplication. git-svn-id: svn://svn.cc65.org/cc65/trunk@4463 b7a2c559-68d2-44c3-8de9-860c34a00d81 2009-11-12 15:48:11 +00:00			`sta ptr3`
			`umul8x8r16m:`
Removed (pretty inconsistently used) tab chars from source code base. 2013-05-09 11:56:54 +00:00			`lda #0 ; Clear byte 1`
			`ldy #8 ; Number of bits`
Fixed the comments to say where the actual Left-Hand Side and Right-Hand Side are put. A description of positions [left, right] is appropriate more for C code than for Assembly code. (A description of timing [first argument, second argument] is more appropriate for the way that Assembly code is written.) 2014-05-11 14:43:06 +00:00			`lsr ptr1 ; Get first bit of RHS into carry`
Added separate 8x8=>16 multiplication routine as start of the multiplication and division stuff cleanup. git-svn-id: svn://svn.cc65.org/cc65/trunk@4431 b7a2c559-68d2-44c3-8de9-860c34a00d81 2009-11-02 22:28:02 +00:00			`@L0: bcc @L1`
			`clc`
			`adc ptr3`
			`@L1: ror`
			`ror ptr1`
			`dey`
			`bne @L0`
Added 16*16=32 multiplication routine. git-svn-id: svn://svn.cc65.org/cc65/trunk@4434 b7a2c559-68d2-44c3-8de9-860c34a00d81 2009-11-03 13:40:03 +00:00			`tax`
Fixed the comments to say where the actual Left-Hand Side and Right-Hand Side are put. A description of positions [left, right] is appropriate more for C code than for Assembly code. (A description of timing [first argument, second argument] is more appropriate for the way that Assembly code is written.) 2014-05-11 14:43:06 +00:00			`stx ptr1+1 ; Result in .XA and ptr1`
Removed (pretty inconsistently used) tab chars from source code base. 2013-05-09 11:56:54 +00:00			`lda ptr1 ; Load the result`
			`rts ; Done`