| Jens Arnold | eb65f89 | 2006-02-22 01:20:45 +0000 | [diff] [blame] | 1 | /*************************************************************************** |
| 2 | * __________ __ ___. |
| 3 | * Open \______ \ ____ ____ | | _\_ |__ _______ ___ |
| 4 | * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / |
| 5 | * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < |
| 6 | * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ |
| 7 | * \/ \/ \/ \/ \/ |
| 8 | * $Id$ |
| 9 | * |
| 10 | * Copyright (C) 2006 by Jens Arnold |
| 11 | * |
| 12 | * All files in this archive are subject to the GNU General Public License. |
| 13 | * See the file COPYING in the source tree root for full license agreement. |
| 14 | * |
| 15 | * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY |
| 16 | * KIND, either express or implied. |
| 17 | * |
| 18 | ****************************************************************************/ |
| 19 | #include "config.h" |
| 20 | |
| 21 | .section .icode,"ax",@progbits |
| 22 | |
| Jens Arnold | eb65f89 | 2006-02-22 01:20:45 +0000 | [diff] [blame] | 23 | .global memset16 |
| 24 | .type memset16,@function |
| 25 | |
| 26 | /* Fills a memory region with specified word value |
| 27 | * Start address must be word aligned, length is in words |
| 28 | * This version is optimized for speed |
| 29 | * |
| 30 | * arguments: |
| 31 | * (4,%sp) - start address |
| 32 | * (8,%sp) - data |
| 33 | * (12,%sp) - length |
| 34 | * |
| 35 | * return value: |
| 36 | * %d0 - start address |
| 37 | * |
| 38 | * register usage: |
| 39 | * %d0 - data (spread to both words when using long stores) |
| 40 | * %d1 - temporary / data (for burst transfer) |
| 41 | * %d2 - data (for burst transfer) |
| 42 | * %d3 - data (for burst transfer) |
| 43 | * %a0 - start address |
| 44 | * %a1 - current address (runs down from end to start) |
| 45 | * |
| 46 | * For maximum speed this routine uses both long stores and burst mode, |
| 47 | * storing whole lines with movem.l. The routine fills memory from end |
| 48 | * to start in order to ease returning the start address. |
| 49 | */ |
| 50 | memset16: |
| 51 | move.l (4,%sp),%a0 /* start address */ |
| 52 | move.l (8,%sp),%d0 /* data */ |
| 53 | move.l (12,%sp),%a1 /* length */ |
| 54 | add.l %a1,%a1 |
| 55 | add.l %a0,%a1 /* %a1 = end address */ |
| 56 | |
| 57 | move.l %a0,%d1 |
| 58 | addq.l #6,%d1 |
| 59 | and.l #0xFFFFFFFC,%d1 /* %d1 = first long bound + 4 */ |
| 60 | cmp.l %d1,%a1 /* at least one aligned longword to fill? */ |
| 61 | blo.b .no_longs /* no, jump directly to word loop */ |
| 62 | |
| 63 | and.l #0xFFFF,%d0 /* start: spread data to both words */ |
| 64 | move.l %d0,%d1 |
| 65 | swap %d1 |
| 66 | or.l %d1,%d0 /* data now in both words */ |
| 67 | |
| 68 | move.l %a1,%d1 |
| 69 | and.l #0xFFFFFFFC,%d1 /* %d1 = last long bound */ |
| 70 | cmp.l %d1,%a1 /* one extra word? */ |
| 71 | bls.b .end_w1 /* no: skip */ |
| 72 | |
| 73 | move.w %d0,-(%a1) /* set leading word */ |
| 74 | |
| 75 | .end_w1: |
| 76 | moveq.l #30,%d1 |
| 77 | add.l %a0,%d1 |
| 78 | and.l #0xFFFFFFF0,%d1 /* %d1 = first line bound + 16 */ |
| 79 | cmp.l %d1,%a1 /* at least one full line to fill? */ |
| 80 | blo.b .no_lines /* no, jump to longword loop */ |
| 81 | |
| 82 | mov.l %a1,%d1 |
| 83 | and.l #0xFFFFFFF0,%d1 /* %d1 = last line bound */ |
| 84 | cmp.l %d1,%a1 /* any longwords to set? */ |
| 85 | bls.b .end_l1 /* no: skip longword loop */ |
| 86 | |
| 87 | /* leading longword loop: sets 0..3 longwords */ |
| 88 | .loop_l1: |
| 89 | move.l %d0,-(%a1) /* store longword */ |
| 90 | cmp.l %d1,%a1 /* runs %a1 down to last line bound */ |
| 91 | bhi.b .loop_l1 |
| 92 | |
| 93 | .end_l1: |
| 94 | move.l %d2,-(%sp) /* free some registers */ |
| 95 | move.l %d3,-(%sp) |
| 96 | |
| 97 | move.l %d0,%d1 /* spread data to 4 data registers */ |
| 98 | move.l %d0,%d2 |
| 99 | move.l %d0,%d3 |
| 100 | lea.l (14,%a0),%a0 /* start address += 14, acct. for trl. data */ |
| 101 | |
| 102 | /* main loop: set whole lines utilising burst mode */ |
| 103 | .loop_line: |
| 104 | lea.l (-16,%a1),%a1 /* pre-decrement */ |
| 105 | movem.l %d0-%d3,(%a1) /* store line */ |
| 106 | cmp.l %a0,%a1 /* runs %a1 down to first line bound */ |
| 107 | bhi.b .loop_line |
| 108 | |
| 109 | lea.l (-14,%a0),%a0 /* correct start address */ |
| 110 | move.l (%sp)+,%d3 /* restore registers */ |
| 111 | move.l (%sp)+,%d2 |
| 112 | |
| 113 | move.l %a0,%d1 /* %d1 = start address ... */ |
| 114 | addq.l #2,%d1 /* ... +2, account for possible trailing word */ |
| 115 | cmp.l %d1,%a1 /* any longwords left */ |
| 116 | bhi.b .loop_l2 /* yes: jump to longword loop */ |
| 117 | bra.b .no_longs /* no: skip loop */ |
| 118 | |
| 119 | .no_lines: |
| 120 | move.l %a0,%d1 /* %d1 = start address ... */ |
| 121 | addq.l #2,%d1 /* ... +2, account for possible trailing word */ |
| 122 | |
| 123 | /* trailing longword loop */ |
| 124 | .loop_l2: |
| 125 | move.l %d0,-(%a1) /* store longword */ |
| 126 | cmp.l %d1,%a1 /* runs %a1 down to first long bound */ |
| 127 | bhi.b .loop_l2 |
| 128 | |
| 129 | .no_longs: |
| 130 | cmp.l %a0,%a1 /* any words left? */ |
| 131 | bls.b .end_w2 /* no: skip loop */ |
| 132 | |
| 133 | /* trailing word loop */ |
| 134 | .loop_w2: |
| 135 | move.w %d0,-(%a1) /* store word */ |
| 136 | cmp.l %a0,%a1 /* runs %a1 down to start address */ |
| 137 | bhi.b .loop_w2 |
| 138 | |
| 139 | .end_w2: |
| 140 | move.l %a0,%d0 /* return start address */ |
| 141 | rts |
| 142 | |
| 143 | .end: |
| 144 | .size memset16,.end-memset16 |