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[/] [zipcpu/] [trunk/] [sw/] [lib/] [divu.S] - Blame information for rev 170

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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
; Filename:     divu.S
;
; Project:      Zip CPU -- a small, lightweight, RISC CPU soft core
;
; Purpose:      Zip assembly file for running doing an unsigned divide.
;               This routine is also called by the signed divide.
;
; Creator:      Dan Gisselquist, Ph.D.
;               Gisselquist Technology, LLC
;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
; Copyright (C) 2015, Gisselquist Technology, LLC
;
; This program is free software (firmware): you can redistribute it and/or
; modify it under the terms of  the GNU General Public License as published
; by the Free Software Foundation, either version 3 of the License, or (at
; your option) any later version.
;
; This program is distributed in the hope that it will be useful, but WITHOUT
; ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or
; FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
; for more details.
;
; License:      GPL, v3, as defined and found on www.gnu.org,
;               http://www.gnu.org/licenses/gpl.html
;
;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
;
;
lib_divu:       ; Given R0,R1, computer R0 = R0/R1 and R1 = R0%R1
        TST     -1,R1
        ; BNZ   divu_valid_divide
        CLR.Z   R0              ; Should be a divide by zero error / trap
        JMP.Z   R2
divu_valid_divide:
        SUB     2,SP
        STO     R2,(SP)
        STO     R3,1(SP)
        ;
        LDI     1,R2    ; Here's where we record the bit we are working on
        CLR     R3      ; Here's where we build our result
; Our original loop rejoin point, before a touch of unrolling
        CMP     R1,R0
        BRC     divu_prep_next_bit
        TST     -1,R1
        BLT     divu_top_bit_set
divu_rotate_up_r1:
        LSL     1,R2
        LSL     1,R1
/*
        CMP     R1,R0
        BRC     divu_prep_next_bit
        TST     -1,R1
        BGT     divu_rotate_up_r1
*/
        BLT     divu_top_bit_set
        CMP     R1,R0
        BRC     divu_prep_next_bit
        ;
        LSL     1,R2
        LSL     1,R1
        BLT     divu_top_bit_set
        CMP     R1,R0
        BRC     divu_prep_next_bit
        ;
        LSL     1,R2
        LSL     1,R1
        BLT     divu_top_bit_set
        CMP     R1,R0
        BRC     divu_prep_next_bit
        ;
        LSL     1,R2
        LSL     1,R1
        BLT     divu_top_bit_set
        CMP     R1,R0
        BRC     divu_prep_next_bit
        BRA     divu_rotate_up_r1
 
divu_top_bit_set:
        CMP     R1,R0
        BRC     divu_prep_next_bit
        SUB     R1,R0
        OR      R2,R3
divu_prep_next_bit:
        LSR     1,R1
        LSR     1,R2
        BZ      divu_record_result
        ;
divu_next_loop:
        CMP     R1,R0           ;
        SUB.GE  R1,R0           ; We also switch to signed arithmetic, since
        OR.GE   R2,R3           ; after the first bit, we are signed
        LSR     1,R1
        LSR     1,R2
        BZ      divu_record_result
        ;
        CMP     R1,R0
        SUB.GE  R1,R0
        OR.GE   R2,R3
        LSR     1,R1
        LSR     1,R2
        BZ      divu_record_result
        ;
        CMP     R1,R0
        SUB.GE  R1,R0
        OR.GE   R2,R3
        LSR     1,R1
        LSR     1,R2
        BZ      divu_record_result
        ;
        CMP     R1,R0
        SUB.GE  R1,R0
        OR.GE   R2,R3
        LSR     1,R1
        LSR     1,R2
        BNZ     divu_next_loop
 
divu_record_result:
        MOV     R0,R1
        MOV     R3,R0
        LOD     (SP),R2
        LOD     1(SP),R3
        ADD     2,SP
        JMP     R2
 

Line No.	Rev	Author	Line
1	59	dgisselq	`;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;`
2	45	dgisselq	`;`
3	59	dgisselq	`; Filename: divu.S`
4	45	dgisselq	`;`
5	59	dgisselq	`; Project: Zip CPU -- a small, lightweight, RISC CPU soft core`
6	45	dgisselq	`;`
7	59	dgisselq	`; Purpose: Zip assembly file for running doing an unsigned divide.`
8			`; This routine is also called by the signed divide.`
9	45	dgisselq	`;`
10	59	dgisselq	`; Creator: Dan Gisselquist, Ph.D.`
11	69	dgisselq	`; Gisselquist Technology, LLC`
12	59	dgisselq	`;`
13			`;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;`
14			`;`
15			`; Copyright (C) 2015, Gisselquist Technology, LLC`
16			`;`
17			`; This program is free software (firmware): you can redistribute it and/or`
18			`; modify it under the terms of the GNU General Public License as published`
19			`; by the Free Software Foundation, either version 3 of the License, or (at`
20			`; your option) any later version.`
21			`;`
22			`; This program is distributed in the hope that it will be useful, but WITHOUT`
23			`; ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or`
24			`; FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License`
25			`; for more details.`
26			`;`
27			`; License: GPL, v3, as defined and found on www.gnu.org,`
28			`; http://www.gnu.org/licenses/gpl.html`
29			`;`
30			`;`
31			`;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;`
32			`;`
33			`;`
34			`;`
35	69	dgisselq	`lib_divu: ; Given R0,R1, computer R0 = R0/R1 and R1 = R0%R1`
36	45	dgisselq	`TST -1,R1`
37			`; BNZ divu_valid_divide`
38			`CLR.Z R0 ; Should be a divide by zero error / trap`
39	69	dgisselq	`JMP.Z R2`
40	45	dgisselq	`divu_valid_divide:`
41	69	dgisselq	`SUB 2,SP`
42			`STO R2,(SP)`
43	45	dgisselq	`STO R3,1(SP)`
44			`;`
45			`LDI 1,R2 ; Here's where we record the bit we are working on`
46			`CLR R3 ; Here's where we build our result`
47			`; Our original loop rejoin point, before a touch of unrolling`
48			`CMP R1,R0`
49			`BRC divu_prep_next_bit`
50			`TST -1,R1`
51			`BLT divu_top_bit_set`
52			`divu_rotate_up_r1:`
53			`LSL 1,R2`
54			`LSL 1,R1`
55			`/*`
56			`CMP R1,R0`
57			`BRC divu_prep_next_bit`
58			`TST -1,R1`
59			`BGT divu_rotate_up_r1`
60			`*/`
61			`BLT divu_top_bit_set`
62			`CMP R1,R0`
63			`BRC divu_prep_next_bit`
64			`;`
65			`LSL 1,R2`
66			`LSL 1,R1`
67			`BLT divu_top_bit_set`
68			`CMP R1,R0`
69			`BRC divu_prep_next_bit`
70			`;`
71			`LSL 1,R2`
72			`LSL 1,R1`
73			`BLT divu_top_bit_set`
74			`CMP R1,R0`
75			`BRC divu_prep_next_bit`
76			`;`
77			`LSL 1,R2`
78			`LSL 1,R1`
79			`BLT divu_top_bit_set`
80			`CMP R1,R0`
81			`BRC divu_prep_next_bit`
82			`BRA divu_rotate_up_r1`
83
84			`divu_top_bit_set:`
85			`CMP R1,R0`
86			`BRC divu_prep_next_bit`
87			`SUB R1,R0`
88			`OR R2,R3`
89			`divu_prep_next_bit:`
90			`LSR 1,R1`
91			`LSR 1,R2`
92			`BZ divu_record_result`
93			`;`
94			`divu_next_loop:`
95			`CMP R1,R0 ;`
96			`SUB.GE R1,R0 ; We also switch to signed arithmetic, since`
97			`OR.GE R2,R3 ; after the first bit, we are signed`
98			`LSR 1,R1`
99			`LSR 1,R2`
100			`BZ divu_record_result`
101			`;`
102			`CMP R1,R0`
103			`SUB.GE R1,R0`
104			`OR.GE R2,R3`
105			`LSR 1,R1`
106			`LSR 1,R2`
107			`BZ divu_record_result`
108			`;`
109			`CMP R1,R0`
110			`SUB.GE R1,R0`
111			`OR.GE R2,R3`
112			`LSR 1,R1`
113			`LSR 1,R2`
114			`BZ divu_record_result`
115			`;`
116			`CMP R1,R0`
117			`SUB.GE R1,R0`
118			`OR.GE R2,R3`
119			`LSR 1,R1`
120			`LSR 1,R2`
121			`BNZ divu_next_loop`
122
123			`divu_record_result:`
124			`MOV R0,R1`
125			`MOV R3,R0`
126	69	dgisselq	`LOD (SP),R2`
127	45	dgisselq	`LOD 1(SP),R3`
128	69	dgisselq	`ADD 2,SP`
129	59	dgisselq	`JMP R2`
130	45	dgisselq

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[/] [zipcpu/] [trunk/] [sw/] [lib/] [divu.S] - Blame information for rev 170