Commit | Line | Data |
---|---|---|
4e07dba7 MS |
1 | #include <linux/linkage.h> |
2 | ||
3 | /* | |
4 | * Unsigned divide operation. | |
5 | * Input : Divisor in Reg r5 | |
6 | * Dividend in Reg r6 | |
7 | * Output: Result in Reg r3 | |
8 | */ | |
9 | ||
10 | .text | |
11 | .globl __udivsi3 | |
12 | .type __udivsi3, @function | |
13 | .ent __udivsi3 | |
14 | ||
15 | __udivsi3: | |
16 | ||
17 | .frame r1, 0, r15 | |
18 | ||
19 | addik r1, r1, -12 | |
20 | swi r29, r1, 0 | |
21 | swi r30, r1, 4 | |
22 | swi r31, r1, 8 | |
23 | ||
24 | beqi r6, div_by_zero /* div_by_zero /* division error */ | |
25 | beqid r5, result_is_zero /* result is zero */ | |
26 | addik r30, r0, 0 /* clear mod */ | |
27 | addik r29, r0, 32 /* initialize the loop count */ | |
28 | ||
29 | /* check if r6 and r5 are equal - if yes, return 1 */ | |
30 | rsub r18, r5, r6 | |
31 | beqid r18, return_here | |
32 | addik r3, r0, 1 | |
33 | ||
34 | /* check if (uns)r6 is greater than (uns)r5. in that case, just return 0 */ | |
35 | xor r18, r5, r6 | |
36 | bgeid r18, 16 | |
37 | add r3, r0, r0 /* we would anyways clear r3 */ | |
38 | blti r6, return_here /* r6[bit 31 = 1] hence is greater */ | |
39 | bri checkr6 | |
40 | rsub r18, r6, r5 /* microblazecmp */ | |
41 | blti r18, return_here | |
42 | ||
43 | /* if r6 [bit 31] is set, then return result as 1 */ | |
44 | checkr6: | |
45 | bgti r6, div0 | |
46 | brid return_here | |
47 | addik r3, r0, 1 | |
48 | ||
49 | /* first part try to find the first '1' in the r5 */ | |
50 | div0: | |
51 | blti r5, div2 | |
52 | div1: | |
53 | add r5, r5, r5 /* left shift logical r5 */ | |
54 | bgtid r5, div1 | |
55 | addik r29, r29, -1 | |
56 | div2: | |
57 | /* left shift logical r5 get the '1' into the carry */ | |
58 | add r5, r5, r5 | |
59 | addc r30, r30, r30 /* move that bit into the mod register */ | |
60 | rsub r31, r6, r30 /* try to subtract (r30 a r6) */ | |
61 | blti r31, mod_too_small | |
62 | /* move the r31 to mod since the result was positive */ | |
63 | or r30, r0, r31 | |
64 | addik r3, r3, 1 | |
65 | mod_too_small: | |
66 | addik r29, r29, -1 | |
67 | beqi r29, loop_end | |
68 | add r3, r3, r3 /* shift in the '1' into div */ | |
69 | bri div2 /* div2 */ | |
70 | loop_end: | |
71 | bri return_here | |
72 | div_by_zero: | |
73 | result_is_zero: | |
74 | or r3, r0, r0 /* set result to 0 */ | |
75 | return_here: | |
76 | /* restore values of csrs and that of r3 and the divisor and the dividend */ | |
77 | lwi r29, r1, 0 | |
78 | lwi r30, r1, 4 | |
79 | lwi r31, r1, 8 | |
80 | rtsd r15, 8 | |
81 | addik r1, r1, 12 | |
82 | ||
83 | .size __udivsi3, . - __udivsi3 | |
84 | .end __udivsi3 |