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.text
/* This is the size of the Clip's RAM, but there is nothing to be gained
(at the moment) by making use of the larger RAM of other targets */
.set DRAM_SIZE, 0x50000
.set GPIOA, 0xC80B0000
.set GPIOB, 0xC80C0000
.set GPIOC, 0xC80D0000
.set GPIOD, 0xC80E0000
.set CGU_PERI, 0xC80F0014
/* Vectors */
ldr pc, =start
.word 0
.word 0
.word 0
.word 0
.word 0
.word 0
.word 0
/* These values are filled in by mkamsboot - don't move them from offset 0x20 */
uclunpack_end: .word 0 /* End of the ucl_unpack function */
uclunpack_size: .word 0 /* Size in bytes of the ucl_unpack function */
ucl_of_end: .word 0 /* End of the ucl-compressed OF image */
ucl_of_size: .word 0 /* Size in bytes of the compressed OF image */
ucl_rb_end: .word 0 /* End of the ucl-compressed RB image */
ucl_rb_size: .word 0 /* Size in bytes of the compressed RB image */
start:
/* First copy the UCL unpack function to the end of RAM */
ldr r0, uclunpack_end /* Source */
ldr r1, uclunpack_size /* Source length */
sub r2, r0, r1 /* Source start - 1*/
ldr r3, =(DRAM_SIZE-1) /* Destination end */
uclcopy:
ldrb r4, [r0], #-1
strb r4, [r3], #-1
cmp r2, r0
bne uclcopy
add r5, r2, #2 /* r5 is entry point of copy of uclunpack */
/* function, plus one (for thumb mode */
/* enable gpio clock */
ldr r0, =CGU_PERI
ldr r1, [r0]
orr r1, r1, #(1<<16)
str r1, [r0]
/* we check A3 unconditionally of the model because it seems to be */
/* either hold, either usb on every model */
ldr r0, =GPIOA
mov r1, #0
str r1, [r0, #0x400]
ldr r1, [r0, #0x20] /* read pin A3 */
cmp r1, #0
bne boot_of
/* here are model specific tests, for dual boot without a computer */
#ifdef SANSA_CLIP
/* HOME button */
ldr r0, =GPIOB
mov r1, #0
str r1, [r0, #0x400]
ldr r1, [r0, #0x10] /* read pin B2 */
cmp r1, #0
bne boot_of
#elif defined(SANSA_E200V2)
/* DOWN button */
ldr r0, =GPIOC
mov r1, #0
str r1, [r0, #0x400]
ldr r1, [r0, #0x100] /* read pin C6 */
cmp r1, #0 /* C6 = #0 means button pressed */
beq boot_of
#else
#error No target-specific key check defined!
#endif
/* No button was held, so we boot rockbox */
ldr r0, ucl_rb_end /* Address of compressed image */
ldr r1, ucl_rb_size /* Compressed size */
b decompress
boot_of:
ldr r0, ucl_of_end /* Address of compressed image */
ldr r1, ucl_of_size /* Compressed size */
decompress:
/* At this point: */
/* r5 = entry point (plus one for thumb) of uclunpack function */
/* r3 = destination_end for copy of UCL image */
/* r0 = source_end for UCL image to copy */
/* r1 = size of UCL image to copy */
sub r4, r3, r1 /* r4 := destination_start - 1 */
fw_copy:
ldrb r2, [r0], #-1
strb r2, [r3], #-1
cmp r3, r4 /* Stop when we reached dest_start-1 */
bne fw_copy
/* Call the ucl decompress function, which will branch to 0x0 */
/* on completion */
add r0, r3, #1 /* r0 := Start of compressed image */
/* r1 already contains compressed size */
mov r2, #0 /* r2 := Destination for unpacking */
bx r5 /* Branch to uclunpack, switching to thumb */
/* never reached */
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