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@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ io_scsd_s.s
@
@ Hardware Routines for reading a Secure Digital card
@ using the SC SD
@
@ Based on code supplied by Romman
@
@ Copyright (c) 2006 Michael "Chishm" Chisholm
@
@ Redistribution and use in source and binary forms, with or without modification,
@ are permitted provided that the following conditions are met:
@
@ 1. Redistributions of source code must retain the above copyright notice,
@ this list of conditions and the following disclaimer.
@ 2. Redistributions in binary form must reproduce the above copyright notice,
@ this list of conditions and the following disclaimer in the documentation and/or
@ other materials provided with the distribution.
@ 3. The name of the author may not be used to endorse or promote products derived
@ from this software without specific prior written permission.
@
@ THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
@ WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
@ AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
@ LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
@ DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
@ LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
@ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
@ (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
@ EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
@
@ 2006-07-22 - Chishm
@ * First release of stable code
@
@ 2006-08-19 - Chishm
@ * Added SuperCard Lite support
@
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
.align 4
.arm
.equ REG_SCSD_DATAWRITE, 0x09000000
.equ BYTES_PER_READ, 0x200
.equ SCSD_STS_BUSY, 0x100
.equ BUSY_WAIT_TIMEOUT, 0x10000
.equ FALSE, 0
.equ TRUE, 1
@ bool _SCSD_writeData_s (u8 *data, u16* crc)
.global _SCSD_writeData_s
_SCSD_writeData_s:
stmfd r13!, {r4-r5}
mov r5, #BYTES_PER_READ
mov r2, #REG_SCSD_DATAWRITE
@ Wait for a free data buffer on the SD card
mov r4, #BUSY_WAIT_TIMEOUT
_SCSD_writeData_busy_wait:
@ Test for timeout
subs r4, r4, #1
moveq r0, #FALSE @ return false on failure
beq _SCSD_writeData_return
@ Check the busy bit of the status register
ldrh r3, [r2]
tst r3, #SCSD_STS_BUSY
beq _SCSD_writeData_busy_wait
ldrh r3, [r2] @ extra clock
mov r3, #0 @ start bit
strh r3,[r2]
@ Check if the data buffer is aligned on a halfword boundary
tst r0, #1
beq _SCSD_writeData_data_loop
@ Used when the source data is unaligned
_SCSD_writeData_data_loop_unaligned:
ldrb r3, [r0], #1
ldrb r4, [r0], #1
orr r3, r3, r4, lsl #8
stmia r2, {r3-r4}
subs r5, r5, #2
bne _SCSD_writeData_data_loop_unaligned
b _SCSD_writeData_crc
@ Write the data to the card
@ 4 halfwords are transmitted to the Supercard at once, for timing purposes
@ Only the first halfword needs to contain data for standard SuperCards
@ For the SuperCard Lite, the data is split into 4 nibbles, one per halfword
_SCSD_writeData_data_loop:
ldrh r3, [r0], #2
@ This bit added for SCLite. Notice that the shift is not the same as in
@ the original (buggy) code supplied by Romman
add r3, r3, r3, lsl #20
mov r4, r3, lsr #8
stmia r2, {r3-r4}
subs r5, r5, #2
bne _SCSD_writeData_data_loop
@ Send the data CRC
_SCSD_writeData_crc:
cmp r1, #0
movne r0, r1
movne r1, #0
movne r5, #8
bne _SCSD_writeData_data_loop
mov r3, #0xff @ end bit
strh r3, [r2]
@ Wait for the SD card to signal that it is finished recieving
mov r4, #BUSY_WAIT_TIMEOUT
_SCSD_writeData_finished_wait:
@ Test for timeout
subs r4, r4, #1
moveq r0, #FALSE @ return false on failure
beq _SCSD_writeData_return
@ Check the busy bit of the status register
ldrh r3, [r2]
tst r3, #0x100
bne _SCSD_writeData_finished_wait
@ Send 8 more clocks, as required by the SD card
ldmia r2, {r3-r4}
@ return true for success
mov r0, #TRUE
_SCSD_writeData_return:
ldmfd r13!,{r4-r5}
bx r14
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