diff options
Diffstat (limited to 'firmware/common/memset_a.S')
-rw-r--r-- | firmware/common/memset_a.S | 55 |
1 files changed, 27 insertions, 28 deletions
diff --git a/firmware/common/memset_a.S b/firmware/common/memset_a.S index bce8936089..e555683474 100644 --- a/firmware/common/memset_a.S +++ b/firmware/common/memset_a.S | |||
@@ -39,7 +39,7 @@ | |||
39 | * register usage: | 39 | * register usage: |
40 | * r0 - temporary | 40 | * r0 - temporary |
41 | * r1 - bit mask for rounding to long bounds | 41 | * r1 - bit mask for rounding to long bounds |
42 | * r2 - last / first long bound (only if >= 12 bytes) | 42 | * r2 - start address +11 for main loop |
43 | * r4 - start address | 43 | * r4 - start address |
44 | * r5 - data (spread to all 4 bytes if >= 12 bytes) | 44 | * r5 - data (spread to all 4 bytes if >= 12 bytes) |
45 | * r6 - current address (runs down from end to start) | 45 | * r6 - current address (runs down from end to start) |
@@ -50,58 +50,57 @@ | |||
50 | */ | 50 | */ |
51 | 51 | ||
52 | _memset: | 52 | _memset: |
53 | neg r4,r0 | ||
54 | and #3,r0 /* r0 = (4 - align_offset) % 4 */ | ||
55 | add #4,r0 | ||
56 | cmp/hs r0,r6 /* at least one aligned longword to fill? */ | ||
53 | add r4,r6 /* r6 = end_address */ | 57 | add r4,r6 /* r6 = end_address */ |
54 | 58 | bf .no_longs /* no, jump directly to byte loop */ | |
55 | mov r6,r0 | ||
56 | add #-12,r0 /* r0 = r6 - 12; don't go below 12 here! */ | ||
57 | cmp/hs r4,r0 /* >= 12 bytes to fill? */ | ||
58 | bf .start_b2 /* no, jump directly to byte loop */ | ||
59 | 59 | ||
60 | extu.b r5,r5 /* start: spread data to all 4 bytes */ | 60 | extu.b r5,r5 /* start: spread data to all 4 bytes */ |
61 | swap.b r5,r0 | 61 | swap.b r5,r0 |
62 | or r0,r5 /* data now in 2 lower bytes of r5 */ | 62 | or r0,r5 /* data now in 2 lower bytes of r5 */ |
63 | swap.w r5,r0 | 63 | swap.w r5,r0 |
64 | or r0,r5 /* data now in all 4 bytes of r5 */ | 64 | or r0,r5 /* data now in all 4 bytes of r5 */ |
65 | 65 | ||
66 | mov #-4,r1 /* r1 = 0xFFFFFFFC */ | 66 | mov #-4,r1 /* r1 = 0xFFFFFFFC */ |
67 | 67 | mov r6,r0 | |
68 | mov r6,r2 | 68 | and r1,r0 /* r0 = last long bound */ |
69 | bra .start_b1 | 69 | cmp/hi r0,r6 /* any leading byte? */ |
70 | and r1,r2 /* r2 = last long bound */ | 70 | bf .end_b1 /* no: skip loop */ |
71 | 71 | ||
72 | /* leading byte loop: sets 0..3 bytes */ | 72 | /* leading byte loop: sets 0..3 bytes */ |
73 | .loop_b1: | 73 | .loop_b1: |
74 | mov.b r5,@-r6 /* store byte */ | 74 | mov.b r5,@-r6 /* store byte */ |
75 | .start_b1: | 75 | cmp/hi r0,r6 |
76 | cmp/hi r2,r6 /* runs r6 down to last long bound */ | 76 | bt .loop_b1 /* runs r6 down to last long bound */ |
77 | bt .loop_b1 | ||
78 | 77 | ||
79 | mov r4,r2 | 78 | .end_b1: |
80 | add #11,r2 /* combined for rounding and offset */ | 79 | mov r4,r2 /* r2 = start_address... */ |
81 | and r1,r2 /* r2 = first long bound + 8 */ | 80 | add #11,r2 /* ... + 11, combined for rounding and offset */ |
81 | xor r2,r0 | ||
82 | tst #4,r0 /* bit 2 tells whether an even or odd number of */ | ||
83 | bf .loop_odd /* longwords to set */ | ||
82 | 84 | ||
83 | /* main loop: set 2 longs per pass */ | 85 | /* main loop: set 2 longs per pass */ |
84 | .loop2_l: | 86 | .loop_2l: |
85 | mov.l r5,@-r6 /* store first long */ | 87 | mov.l r5,@-r6 /* store first long */ |
86 | cmp/hi r2,r6 /* runs r6 down to first or second long bound */ | 88 | .loop_odd: |
89 | cmp/hi r2,r6 /* runs r6 down to first long bound */ | ||
87 | mov.l r5,@-r6 /* store second long */ | 90 | mov.l r5,@-r6 /* store second long */ |
88 | bt .loop2_l | 91 | bt .loop_2l |
89 | |||
90 | add #-8,r2 /* correct offset */ | ||
91 | cmp/hi r2,r6 /* 1 long left? */ | ||
92 | bf .start_b2 /* no, jump to trailing byte loop */ | ||
93 | 92 | ||
94 | bra .start_b2 /* jump to trailing byte loop */ | 93 | .no_longs: |
95 | mov.l r5,@-r6 /* store last long */ | 94 | cmp/hi r4,r6 /* any bytes left? */ |
95 | bf .end_b2 /* no: skip loop */ | ||
96 | 96 | ||
97 | /* trailing byte loop */ | 97 | /* trailing byte loop */ |
98 | .align 2 | ||
99 | .loop_b2: | 98 | .loop_b2: |
100 | mov.b r5,@-r6 /* store byte */ | 99 | mov.b r5,@-r6 /* store byte */ |
101 | .start_b2: | ||
102 | cmp/hi r4,r6 /* runs r6 down to the start address */ | 100 | cmp/hi r4,r6 /* runs r6 down to the start address */ |
103 | bt .loop_b2 | 101 | bt .loop_b2 |
104 | 102 | ||
103 | .end_b2: | ||
105 | rts | 104 | rts |
106 | mov r4,r0 /* return start address */ | 105 | mov r4,r0 /* return start address */ |
107 | 106 | ||