rockbox/firmware/target/coldfire/iaudio/lcd-remote-as-iaudio.S
Jens Arnold 06ec18d93f Slightly better instruction order, added comment.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@16833 a1c6a512-1295-4272-9138-f99709370657
2008-03-26 23:45:55 +00:00

318 lines
8.3 KiB
ArmAsm

/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2008 by Jens Arnold
*
* All files in this archive are subject to the GNU General Public License.
* See the file COPYING in the source tree root for full license agreement.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#define CLOCK_MASK 0x00004000
#define DATA_MASK 0x00002000
#define RS_MASK 0x00008000
#define GPIO_OUT_ADDR 0x80000004
#define CS_MASK 0x00000020
#define GPIO1_OUT_ADDR 0x800000b4
.extern cpu_frequency /* Global variable from system.c */
.section .icode,"ax",@progbits
/* Output 8 bits to the LCD. Instruction order is devised to maximize the
* delay between changing the data line and the CLK L->H transition, which
* makes the LCD controller sample DATA.
* Requires CLK = 1 on entry.
*
* Custom calling convention:
* %a0 - GPIO_OUT_ADDR
* %d3 - data byte
* %d6 - DATA_MASK
* %d7 - CLOCK_MASK
* Clobbers:
* %d0..%d3
*/
.write_byte:
move.w %sr, %d2
move.w #0x2700, %sr
move.l (%a0), %d0 /* Get current state of data port */
move.l %d0, %d1
and.l %d6, %d1 /* Check current state of data line */
beq.s 1f /* and set it as previous-state bit */
bset #8, %d3
1:
move.l %d3, %d1 /* Compute the 'bit derivative', i.e. a value */
lsr.l #1, %d1 /* with 1's where the data changes from the */
eor.l %d1, %d3 /* previous state, and 0's where it doesn't */
swap %d3 /* Shift data to upper byte */
lsl.l #8, %d3
eor.l %d7, %d0 /* precalculate opposite state of clock line */
lsl.l #1,%d3 /* Shift out MSB */
bcc.s 1f
eor.l %d6, %d0 /* 1: Flip data bit */
1:
move.l %d0, (%a0) /* Output new state and set CLK = 0*/
move.l %d0, %d1
eor.l %d7, %d1
bra.w .wr_bit7
/* Output 16 bits to the LCD. Instruction order is devised to maximize the
* delay between changing the data line and the CLK L->H transition, which
* makes the LCD controller sample DATA.
* Requires CLK = 1 on entry.
*
* Custom calling convention:
* %a0 - GPIO_OUT_ADDR
* %d3 - data word
* %d6 - DATA_MASK
* %d7 - CLOCK_MASK
* Clobbers:
* %d0..%d3
*/
.write_word:
move.w %sr, %d2
move.w #0x2700, %sr
move.l (%a0), %d0 /* Get current state of data port */
move.l %d0, %d1
and.l %d6, %d1 /* Check current state of data line */
beq.s 1f /* and set it as previous-state bit */
bset #16, %d3
1:
move.l %d3, %d1 /* Compute the 'bit derivative', i.e. a value */
lsr.l #1, %d1 /* with 1's where the data changes from the */
eor.l %d1, %d3 /* previous state, and 0's where it doesn't */
swap %d3 /* Shift data to upper word */
eor.l %d7, %d0 /* precalculate opposite state of clock line */
lsl.l #1,%d3 /* Shift out MSB */
bcc.s 1f
eor.l %d6, %d0 /* 1: Flip data bit */
1:
move.l %d0, (%a0) /* Output new state and set CLK = 0*/
move.l %d0, %d1
eor.l %d7, %d1
nop
.macro bit_out
lsl.l #1,%d3
bcc.s 1f
eor.l %d6, %d0
1:
move.l %d1, (%a0) /* Set CLK = 1 (delayed) */
move.l %d0, (%a0)
move.l %d0, %d1
eor.l %d7, %d1
.endm
bit_out
nop
bit_out
nop
bit_out
nop
bit_out
nop
bit_out
nop
bit_out
nop
bit_out
nop
bit_out
nop
.wr_bit7:
bit_out
nop
bit_out
nop
bit_out
nop
bit_out
nop
bit_out
nop
bit_out
nop
bit_out
nop
nop
move.l %d1, (%a0) /* Set CLK = 1 (delayed) */
move.w %d2, %sr
rts
/* Output 16 bits to the LCD as fast as possible. Use only at < 60MHz.
*
* Custom calling convention:
* %a0 - GPIO_OUT_ADDR
* %d3 - data word
* %d6 - DATA_MASK
* %d7 - CLOCK_MASK
* Clobbers:
* %d0..%d3
*/
.write_word_fast:
move.w %sr, %d2 /* Get current interrupt level */
move.w #0x2700, %sr /* Disable interrupts */
move.l (%a0), %d0 /* Get current state of data port */
move.l %d0, %d1
and.l %d6, %d1 /* Check current state of data line */
beq.s 1f /* and set it as previous-state bit */
bset #16, %d3
1:
move.l %d3, %d1 /* Compute the 'bit derivative', i.e. a value */
lsr.l #1, %d1 /* with 1's where the data changes from the */
eor.l %d1, %d3 /* previous state, and 0's where it doesn't */
swap %d3 /* Shift data to upper byte */
move.l %d0, %d1 /* precalculate opposite state of clock line */
eor.l %d7, %d1
.macro bit_out_fast
lsl.l #1,%d3 /* Shift out MSB */
bcc.s 1f
eor.l %d6, %d0 /* 1: Flip data bit */
eor.l %d6, %d1 /* for both clock states */
1:
move.l %d1, (%a0) /* Output new state and set CLK = 0*/
move.l %d0, (%a0) /* set CLK = 1 */
.endm
bit_out_fast
bit_out_fast
bit_out_fast
bit_out_fast
bit_out_fast
bit_out_fast
bit_out_fast
bit_out_fast
bit_out_fast
bit_out_fast
bit_out_fast
bit_out_fast
bit_out_fast
bit_out_fast
bit_out_fast
bit_out_fast
move.w %d2, %sr /* Restore interrupt level */
rts
.global lcd_remote_write_command
.type lcd_remote_write_command, @function
lcd_remote_write_command:
lea.l (-4*4, %sp), %sp
movem.l %d2-%d3/%d6-%d7, (%sp)
move.l (4*4+4, %sp), %d3 /* cmd */
lea.l GPIO_OUT_ADDR, %a0
lea.l GPIO1_OUT_ADDR, %a1
move.l #DATA_MASK, %d6
move.l #CLOCK_MASK, %d7
move.l #~RS_MASK, %d0
and.l %d0, (%a0)
move.l #~CS_MASK, %d0
and.l %d0, (%a1)
bsr.w .write_byte
move.l #CS_MASK, %d0
or.l %d0, (%a1)
movem.l (%sp), %d2-%d3/%d6-%d7
lea.l (4*4, %sp), %sp
rts
.global lcd_remote_write_command_ex
.type lcd_remote_write_command_ex, @function
lcd_remote_write_command_ex:
lea.l (-4*4, %sp), %sp
movem.l %d2-%d3/%d6-%d7, (%sp)
movem.l (4*4+4, %sp), %d2-%d3 /* cmd, data */
lea.l GPIO_OUT_ADDR, %a0
lea.l GPIO1_OUT_ADDR, %a1
move.l #DATA_MASK, %d6
move.l #CLOCK_MASK, %d7
move.l #~RS_MASK, %d0
and.l %d0, (%a0)
move.l #~CS_MASK, %d0
and.l %d0, (%a1)
lsl.l #8, %d2
or.l %d2, %d3
bsr.w .write_word
move.l #CS_MASK, %d0
or.l %d0, (%a1)
movem.l (%sp), %d2-%d3/%d6-%d7
lea.l (4*4, %sp), %sp
rts
.global lcd_remote_write_data
.type lcd_remote_write_data, @function
lcd_remote_write_data:
lea.l (-7*4, %sp), %sp
movem.l %d2-%d4/%d6-%d7/%a2-%a3, (%sp)
move.l (7*4+4, %sp), %a2 /* p_words */
move.l (7*4+8, %sp), %d4 /* count */
lea.l GPIO_OUT_ADDR, %a0
lea.l GPIO1_OUT_ADDR, %a1
move.l #DATA_MASK, %d6
move.l #CLOCK_MASK, %d7
lea.l .write_word, %a3
move.l cpu_frequency, %d0
cmp.l #60000000, %d0
bhi.b 1f
lea.l .write_word_fast, %a3
1:
move.l #RS_MASK, %d0
or.l %d0, (%a0)
move.l #~CS_MASK, %d0
and.l %d0, (%a1)
.wd_loop:
clr.l %d3
move.w (%a2)+, %d3
jsr (%a3)
subq.l #1, %d4
bne.s .wd_loop
move.l #CS_MASK, %d0
or.l %d0, (%a1)
movem.l (%sp), %d2-%d4/%d6-%d7/%a2-%a3
lea.l (7*4, %sp), %sp
rts