/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 *
 * Copyright (C) 2006 by Jens Arnold
 * Copyright (C) 2010 by Marcin Bukat (byte swaps)
 *
 * This program is free software; 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 2
 * of the License, or (at your option) any later version.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/

#include "config.h"

    .macro SWAP_BYTES dn
        move.l  %a3, %d7        | d7 = 0x00FF00FF
        and.l   \dn, %d7        | d7 = .B.D
        eor.l   %d7, \dn        | dn = A.C.
        lsl.l   #8, %d7         | d7 = B.D.
        lsr.l   #8, \dn         | d3 = .A.C
        or.l    %d7, \dn        | dn = BADC
    .endm

    .equ    .ata_port, 0x20000020
    .equ    .swapmask, 0x00FF00FF

    .section    .icode,"ax",@progbits

    .align  2
    .global copy_read_sectors
    .type   copy_read_sectors,@function
    
/* Read a number of words from the ATA data port
 *
 * Utilises line bursts, assumes there is at least one full line to copy.
 *
 * Arguments:
 *   (4,%sp) - buffer address
 *   (8,%sp) - word count
 *
 * Register usage:
 *   %a0 - current address
 *   %a1 - end address
 *   %a2 - ata port
 *   %d0 - scratch
 *   %d1 - shift count
 *   %d2-%d6 - read buffers
 *
 *   #ifdef ATA_SWAP_WORDS
 *   %d7 - byte swap scrach
 *   %a3 - byte swap mask
 *   #endif
 */

copy_read_sectors:
#ifdef ATA_SWAP_WORDS
    lea.l   (-32, %sp), %sp
    movem.l %d2-%d7/%a2-%a3, (%sp)
    movem.l (36, %sp), %a0-%a1
    lea.l   .swapmask, %a3
#else
    lea.l   (-24, %sp), %sp
    movem.l %d2-%d6/%a2, (%sp)
    movem.l (28, %sp), %a0-%a1
#endif
    add.l   %a1, %a1
    add.l   %a0, %a1
    lea.l   .ata_port, %a2

    move.l  %a0, %d0
    btst.l  #0, %d0         /* 16-bit aligned? */
    jeq     .r_aligned      /* yes, do word copy */

    /* not 16-bit aligned */
    subq.l  #1, %a1         /* last byte is done unconditionally */
    moveq.l #24, %d1        /* preload shift count */

    move.w  (%a2), %d2      /* load initial word */
#ifdef ATA_SWAP_WORDS
    move.b  %d2, (%a0)+
    lsr.l   #8, %d2
#else
    move.l  %d2, %d3
    lsr.l   #8, %d3
    move.b  %d3, (%a0)+     /* write high byte of it, aligns dest addr */
#endif
    btst.l  #1, %d0         /* longword aligned? (testing old d0 value!) */
    bne.b   .r_end_u_w1     /* yes, skip leading word handling */
#ifdef ATA_SWAP_WORDS
    move.w  (%a2), %d3
    lsl.l   #8, %d2
    move.b  %d3, %d2
    move.w  %d2, (%a0)+     /* write bytes 2 and 3 as word */
    move.l  %d3, %d2
    lsr.l   #8, %d2
#else
    swap    %d2             /* move initial word up */
    move.w  (%a2), %d2      /* combine with second word */
    move.l  %d2, %d3
    lsr.l   #8, %d3
    move.w  %d3, (%a0)+     /* write bytes 2 and 3 as word */
#endif

.r_end_u_w1:
    moveq.l #12, %d0
    add.l   %a0, %d0
    and.l   #0xFFFFFFF0,%d0 /* d0 == first line bound */
    cmp.l   %a0, %d0        /* any leading longwords? */
    bls.b   .r_end_u_l1     /* no: skip loop */

.r_loop_u_l1:
    move.w  (%a2), %d3      /* load first word */
    swap    %d3             /* move to upper 16 bit */
    move.w  (%a2), %d3      /* load second word */

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d3
#endif

    move.l  %d3, %d4
    lsl.l   %d1, %d2
    lsr.l   #8, %d3
    or.l    %d3, %d2        /* combine old low byte with new top 3 bytes */
    move.l  %d2, (%a0)+     /* store as long */
    move.l  %d4, %d2
    cmp.l   %a0, %d0        /* run up to first line bound */
    bhi.b   .r_loop_u_l1

.r_end_u_l1:
    lea.l   (-14, %a1), %a1 /* adjust end addr. to 16 bytes/pass */

.r_loop_u_line:
    move.w  (%a2), %d3      /* load 1st word */
    swap    %d3             /* move to upper 16 bit */
    move.w  (%a2), %d3      /* load 2nd word */

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d3
#endif

    move.l  %d3, %d0
    lsl.l   %d1, %d2
    lsr.l   #8, %d0
    or.l    %d0, %d2        /* combine old low byte with new top 3 bytes */
    move.w  (%a2), %d4      /* load 3rd word */
    swap    %d4             /* move to upper 16 bit */
    move.w  (%a2), %d4      /* load 4th word */

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d4
#endif

    move.l  %d4, %d0
    lsl.l   %d1, %d3
    lsr.l   #8, %d0
    or.l    %d0, %d3        /* combine old low byte with new top 3 bytes */
    move.w  (%a2), %d5      /* load 5th word */
    swap    %d5             /* move to upper 16 bit */
    move.w  (%a2), %d5      /* load 6th word */

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d5
#endif

    move.l  %d5, %d0
    lsl.l   %d1, %d4
    lsr.l   #8, %d0
    or.l    %d0, %d4        /* combine old low byte with new top 3 bytes */
    move.w  (%a2), %d6      /* load 7th word */
    swap    %d6             /* move to upper 16 bit */
    move.w  (%a2), %d6      /* load 8th word */

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d6
#endif

    move.l  %d6, %d0
    lsl.l   %d1, %d5
    lsr.l   #8, %d0
    or.l    %d0, %d5        /* combine old low byte with new top 3 bytes */
    movem.l %d2-%d5, (%a0)  /* store line */
    lea.l   (16, %a0), %a0
    move.l  %d6, %d2
    cmp.l   %a0, %a1        /* run up to last line bound */
    bhi.b   .r_loop_u_line

    lea.l   (12, %a1), %a1  /* readjust for longword loop */
    cmp.l   %a0, %a1        /* any trailing longwords? */
    bls.b   .r_end_u_l2     /* no: skip loop */

.r_loop_u_l2:
    move.w  (%a2), %d3      /* load first word */
    swap    %d3             /* move to upper 16 bit */
    move.w  (%a2), %d3      /* load second word */

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d3
#endif

    move.l  %d3, %d4
    lsl.l   %d1, %d2
    lsr.l   #8, %d3
    or.l    %d3, %d2        /* combine old low byte with new top 3 bytes */
    move.l  %d2, (%a0)+     /* store as long */
    move.l  %d4, %d2
    cmp.l   %a0, %a1        /* run up to last long bound */
    bhi.b   .r_loop_u_l2
        
.r_end_u_l2:
    blo.b   .r_end_u_w2     /* one word left? */

#ifdef ATA_SWAP_WORDS
    move.w  (%a2), %d3
    lsl.l   #8, %d2
    move.b  %d3, %d2
    move.w  %d2, (%a0)+     /* write bytes 2 and 3 as word */
    move.l  %d3, %d2
    lsr.l   #8, %d2
.r_end_u_w2:
    move.b  %d2, (%a0)+     /* store final byte */
    bra.w   .r_exit
#else
    swap    %d2             /* move old word to upper 16 bits */
    move.w  (%a2), %d2      /* load final word */
    move.l  %d2, %d3
    lsr.l   #8, %d3
    move.w  %d3, (%a0)+     /* write bytes 2 and 3 as word */
.r_end_u_w2:
    move.b  %d2, (%a0)+     /* store final byte */
    bra.b   .r_exit
#endif

    /* 16-bit aligned */
.r_aligned:
    btst.l  #1, %d0         /* longword aligned? */
    beq.b   .r_end_a_w1     /* yes, skip leading word handling */

#ifdef ATA_SWAP_WORDS
    move.w  (%a2), %d7      /* copy initial word after byte swap */
    move.b  %d7, (%a0)+
    lsr.l   #8, %d7
    move.b  %d7, (%a0)+
#else
    move.w  (%a2), (%a0)+   /* copy initial word */
#endif
.r_end_a_w1:
    moveq.l #12, %d0
    add.l   %a0, %d0
    and.l   #0xFFFFFFF0,%d0 /* d0 == first line bound */
    cmp.l   %a0, %d0        /* any leading longwords? */
    bls.b   .r_end_a_l1     /* no: skip loop */

.r_loop_a_l1:
    move.w  (%a2), %d1      /* load first word */
    swap    %d1             /* move it to upper 16 bits */
    move.w  (%a2), %d1      /* load second word */

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d1
#endif

    move.l  %d1, (%a0)+     /* store as long */
    cmp.l   %a0, %d0        /* run up to first line bound */
    bhi.b   .r_loop_a_l1

.r_end_a_l1:
    lea.l   (-14, %a1), %a1 /* adjust end addr. to 16 bytes/pass */

.r_loop_a_line:
    move.w  (%a2), %d0      /* load 1st word */
    swap    %d0             /* move it to upper 16 bits */
    move.w  (%a2), %d0      /* load 2nd word */
    move.w  (%a2), %d1      /* load 3rd word */
    swap    %d1             /* move it to upper 16 bits */
    move.w  (%a2), %d1      /* load 4th word */
    move.w  (%a2), %d2      /* load 5th word */
    swap    %d2             /* move it to upper 16 bits */
    move.w  (%a2), %d2      /* load 6th word */
    move.w  (%a2), %d3      /* load 7th word */
    swap    %d3             /* move it to upper 16 bits */
    move.w  (%a2), %d3      /* load 8th word */

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d0
    SWAP_BYTES %d1
    SWAP_BYTES %d2
    SWAP_BYTES %d3
#endif

    movem.l %d0-%d3, (%a0)  /* store line */
    lea.l   (16, %a0), %a0
    cmp.l   %a0, %a1        /* run up to last line bound */
    bhi.b   .r_loop_a_line

    lea.l   (12, %a1), %a1  /* readjust for longword loop */
    cmp.l   %a0, %a1        /* any trailing longwords? */
    bls.b   .r_end_a_l2     /* no: skip loop */

.r_loop_a_l2:
    move.w  (%a2), %d1      /* read first word */
    swap    %d1             /* move it to upper 16 bits */
    move.w  (%a2), %d1      /* read second word */

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d1
#endif

    move.l  %d1, (%a0)+     /* store as long */
    cmp.l   %a0, %a1        /* run up to last long bound */
    bhi.b   .r_loop_a_l2
        
.r_end_a_l2:
    blo.b   .r_end_a_w2     /* one word left? */

#ifdef ATA_SWAP_WORDS
    move.w (%a2), %d7      /* copy final word after byte swap */
    move.b %d7, (%a0)+
    lsr.l  #8, %d7
    move.b %d7, (%a0)+
#else
    move.w  (%a2), (%a0)+   /* copy final word */
#endif
.r_end_a_w2:

.r_exit:
#ifdef ATA_SWAP_WORDS
    movem.l (%sp), %d2-%d7/%a2-%a3
    lea.l   (32, %sp), %sp
#else
    movem.l (%sp), %d2-%d6/%a2
    lea.l   (24, %sp), %sp
#endif
    rts

.r_end:
    .size   copy_read_sectors,.r_end-copy_read_sectors

    .align  2
    .global copy_write_sectors
    .type   copy_write_sectors,@function
    
/* Write a number of words to the ATA data port
 *
 * Utilises line bursts, assumes there is at least one full line to copy.
 *
 * Arguments:
 *   (4,%sp) - buffer address
 *   (8,%sp) - word count
 *
 * Register usage:
 *   %a0 - current address
 *   %a1 - end address
 *   %a2 - ata port
 *   %d0 - scratch
 *   %d1 - shift count
 *   %d2-%d6 - read buffers
 *
 *   #ifdef ATA_SWAP_WORDS
 *   %d7 - swap scrach
 *   %a3 - swap mask
 *   #endif
 */

copy_write_sectors:
#ifdef ATA_SWAP_WORDS
    lea.l   (-32, %sp), %sp
    movem.l %d2-%d7/%a2-%a3, (%sp)
    movem.l (36, %sp), %a0-%a1
    lea.l   .swapmask, %a3
#else
    lea.l   (-24, %sp), %sp
    movem.l %d2-%d6/%a2, (%sp)
    movem.l (28, %sp), %a0-%a1
#endif
    add.l   %a1, %a1
    add.l   %a0, %a1
    lea.l   .ata_port, %a2

    move.l  %a0, %d0
    btst.l  #0, %d0         /* 16-bit aligned? */
    jeq     .w_aligned      /* yes, do word copy */

    /* not 16-bit aligned */
    subq.l  #1, %a1         /* last byte is done unconditionally */
    moveq.l #24, %d1        /* preload shift count */

    move.b  (%a0)+, %d2

    btst.l  #1, %d0         /* longword aligned? (testing old d0 value!) */
    bne.b   .w_end_u_w1     /* yes, skip leading word handling */

    swap    %d2
    move.w  (%a0)+, %d2
    move.l  %d2, %d3
    lsr.l   #8, %d3

#ifdef ATA_SWAP_WORDS
    move.l  %d3, %d7       /* byte swap low word of %d3 */
    lsr.l   #8, %d7
    lsl.l   #8, %d3
    move.b  %d7, %d3
#endif

    move.w  %d3, (%a2)
        
.w_end_u_w1:
    moveq.l #12, %d0
    add.l   %a0, %d0
    and.l   #0xFFFFFFF0,%d0 /* d0 == first line bound */
    cmp.l   %a0, %d0        /* any leading longwords? */
    bls.b   .w_end_u_l1     /* no: skip loop */
        
.w_loop_u_l1:
    move.l  (%a0)+, %d3
    move.l  %d3, %d4
    lsl.l   %d1, %d2
    lsr.l   #8, %d3
    or.l    %d3, %d2

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d2
#endif

    swap    %d2
    move.w  %d2, (%a2)
    swap    %d2
    move.w  %d2, (%a2)
    move.l  %d4, %d2
    cmp.l   %a0, %d0        /* run up to first line bound */
    bhi.b   .w_loop_u_l1

.w_end_u_l1:
    lea.l   (-14, %a1), %a1 /* adjust end addr. to 16 bytes/pass */

.w_loop_u_line:
    movem.l (%a0), %d3-%d6
    lea.l   (16, %a0), %a0
    move.l  %d3, %d0
    lsl.l   %d1, %d2
    lsr.l   #8, %d0
    or.l    %d0, %d2

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d2
#endif

    swap    %d2
    move.w  %d2, (%a2)
    swap    %d2
    move.w  %d2, (%a2)
    move.l  %d4, %d0
    lsl.l   %d1, %d3
    lsr.l   #8, %d0
    or.l    %d0, %d3

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d3
#endif

    swap    %d3
    move.w  %d3, (%a2)
    swap    %d3
    move.w  %d3, (%a2)
    move.l  %d5, %d0
    lsl.l   %d1, %d4
    lsr.l   #8, %d0
    or.l    %d0, %d4

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d4
#endif

    swap    %d4
    move.w  %d4, (%a2)
    swap    %d4
    move.w  %d4, (%a2)
    move.l  %d6, %d0
    lsl.l   %d1, %d5
    lsr.l   #8, %d0
    or.l    %d0, %d5

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d5
#endif

    swap    %d5
    move.w  %d5, (%a2)
    swap    %d5
    move.w  %d5, (%a2)
    move.l  %d6, %d2
    cmp.l   %a0, %a1        /* run up to last line bound */
    bhi.b   .w_loop_u_line

    lea.l   (12, %a1), %a1  /* readjust for longword loop */
    cmp.l   %a0, %a1        /* any trailing longwords? */
    bls.b   .w_end_u_l2     /* no: skip loop */

.w_loop_u_l2:
    move.l  (%a0)+, %d3
    move.l  %d3, %d4
    lsl.l   %d1, %d2
    lsr.l   #8, %d3
    or.l    %d3, %d2

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d2
#endif

    swap    %d2
    move.w  %d2, (%a2)
    swap    %d2
    move.w  %d2, (%a2)
    move.l  %d4, %d2
    cmp.l   %a0, %a1        /* run up to first line bound */
    bhi.b   .w_loop_u_l2

.w_end_u_l2:
    blo.b   .w_end_u_w2     /* one word left? */

    swap    %d2
    move.w  (%a0)+, %d2
    move.l  %d2, %d3
    lsr.l   #8, %d3

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d3
#endif

    move.w  %d3, (%a2)

.w_end_u_w2:
#ifdef ATA_SWAP_WORDS
    move.l  %d2, %d7
    move.b  (%a0)+, %d2
    lsl.l   #8, %d2
    move.b  %d7, %d2
    move.w  %d2, (%a2)
    bra.w    .w_exit
#else
    lsl.l   #8, %d2
    move.b  (%a0)+, %d2
    move.w  %d2, (%a2)
    bra.b    .w_exit
#endif

    /* 16-bit aligned */
.w_aligned:
    btst.l  #1, %d0
    beq.b   .w_end_a_w1

#ifdef ATA_SWAP_WORDS
    move.w  (%a0)+, %d1    /* copy initial word bytes swaped */
    move.l  %d1, %d7
    lsl.l   #8, %d1
    lsr.l   #8, %d7
    move.b  %d7, %d1
    move.w  %d1, (%a2)
#else
    move.w  (%a0)+, (%a2)   /* copy initial word */
#endif

.w_end_a_w1:
    moveq.l #12, %d0
    add.l   %a0, %d0
    and.l   #0xFFFFFFF0,%d0 /* d0 == first line bound */
    cmp.l   %a0, %d0        /* any leading longwords? */
    bls.b   .w_end_a_l1     /* no: skip loop */

.w_loop_a_l1:
    move.l  (%a0)+, %d1

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d1
#endif

    swap    %d1
    move.w  %d1, (%a2)
    swap    %d1
    move.w  %d1, (%a2)
    cmp.l   %a0, %d0        /* run up to first line bound */
    bhi.b   .w_loop_a_l1

.w_end_a_l1:
    lea.l   (-14, %a1), %a1 /* adjust end addr. to 16 bytes/pass */

.w_loop_a_line:
    movem.l (%a0), %d0-%d3
    lea.l   (16, %a0), %a0

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d0
    SWAP_BYTES %d1
    SWAP_BYTES %d2
    SWAP_BYTES %d3
#endif

    swap    %d0
    move.w  %d0, (%a2)
    swap    %d0
    move.w  %d0, (%a2)
    swap    %d1
    move.w  %d1, (%a2)
    swap    %d1
    move.w  %d1, (%a2)
    swap    %d2
    move.w  %d2, (%a2)
    swap    %d2
    move.w  %d2, (%a2)
    swap    %d3
    move.w  %d3, (%a2)
    swap    %d3
    move.w  %d3, (%a2)
    cmp.l   %a0, %a1        /* run up to last line bound */
    bhi.b   .w_loop_a_line
        
    lea.l   (12, %a1), %a1  /* readjust for longword loop */
    cmp.l   %a0, %a1        /* any trailing longwords? */
    bls.b   .w_end_a_l2     /* no: skip loop */

.w_loop_a_l2:
    move.l  (%a0)+, %d1

#ifdef ATA_SWAP_WORDS
    SWAP_BYTES %d1
#endif

    swap    %d1
    move.w  %d1, (%a2)
    swap    %d1
    move.w  %d1, (%a2)
    cmp.l   %a0, %a1        /* run up to first line bound */
    bhi.b   .w_loop_a_l2

.w_end_a_l2:
    blo.b   .w_end_a_w2     /* one word left? */

#ifdef ATA_SWAP_WORDS
    move.w  (%a0)+, %d0    /* copy final word after byte swap */
    move.l  %d0, %d7
    lsl.l   #8, %d0
    lsr.l   #8, %d7
    move.b  %d7, %d0
    move.w  %d0, (%a2)
#else
    move.w  (%a0)+, (%a2)   /* copy final word */
#endif

.w_end_a_w2:

.w_exit:
#ifdef ATA_SWAP_WORDS
    movem.l (%sp), %d2-%d7/%a2-%a3
    lea.l   (32, %sp), %sp
#else
    movem.l (%sp), %d2-%d6/%a2
    lea.l   (24, %sp), %sp
#endif
    rts

.w_end:
    .size   copy_write_sectors,.w_end-copy_write_sectors
