164 lines
2.3 KiB
ArmAsm
164 lines
2.3 KiB
ArmAsm
.text
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.global _start
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_start:
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// ldr r0, =0x7000cffc // stack_start
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// mov sp, r0
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// mov r2, #0xffffffff
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// ldr r1, =0x7000c000 // stack_end
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//
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//clear_stack:
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// cmp r1, r0
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// str r2, [r0]
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// sub r0, r0, #4
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// bcc clear_stack
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//
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// bl wdt_disable
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//
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//clear_psram:
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// mov r0, #0
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// mov r1, #0x00800000
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// mov r2, #0
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//clear_psram_loop:
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// cmp r1, r0
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// str r2, [r0], #4
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// bcc clear_psram_loop
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//print_welcome_banner:
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// adr r0, welcome_banner
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// bl uart_puts
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main_loop:
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adr r0, four_byte_buffer
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mov r1, #1
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mvn r2, #0
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ldr r3, =0xfff03639
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blx r3
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adr r0, four_byte_buffer
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mov r1, #1
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mvn r2, #0
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ldr r3, =0xfff03653
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blx r3
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ldr r3, =0xfff04845
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blx r3
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b main_loop
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.align 4
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four_byte_buffer:
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.ascii "1234"
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load_program:
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bl uart_getc
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mov r5, r0
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lsls r5, r5, #0
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mov r4, r5
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bl uart_getc
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mov r5, r0
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lsls r5, r5, #8
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orr r4, r5
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bl uart_getc
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mov r5, r0
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lsls r5, r5, #16
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orr r4, r5
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bl uart_getc
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mov r5, r0
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lsls r5, r5, #24
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orr r4, r5
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# r4 now contains the number of bytes to load.
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# r5 contains the current offset to write to.
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# Load bytes from the serial port into RAM.
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mov r5, #0
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loader_loop:
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bl uart_getc
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strb r0, [r5], #1
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sub r4, #1
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cmp r4, #0
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bne loader_loop
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jump_to_new_program:
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adr r0, launch_message
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bl uart_puts
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mov r0, #0
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mov pc, r0
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.align 4
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welcome_banner:
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.ascii "Fernvale bootloader\r\nWrite four bytes of program size, then\r\n"
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.asciz "write program data...\r\n>"
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launch_message:
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.asciz "Launching program...\r\n"
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.align 4
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uart_putc:
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push {lr}
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sub sp, sp, #12
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add r3, sp, #8
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strb r0, [r3, #-4]!
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mov r0, r3
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mov r1, #1
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mvn r2, #0
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ldr r3, =0x70004560
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ldr r3, [r3]
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blx r3
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add sp, sp, #12
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pop {pc}
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uart_puts:
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push {lr}
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mov r3, r0
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mov r2, r0
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mov r1, #0
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uart_puts_count_chars_loop:
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ldrb r0, [r3], #1
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cmp r0, #0
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beq uart_puts_print
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add r1, r1, #1
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b uart_puts_count_chars_loop
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uart_puts_print:
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mov r0, r2
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mvn r2, #0
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// Call usb_uart_write(char *data, int bytes, int timeout)
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ldr r3, =0x70004560
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ldr r3, [r3]
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blx r3
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ldr r3, =0x70004564
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ldr r3, [r3]
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cmp r3, #0
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beq uart_puts_exit
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blx r3
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uart_puts_exit:
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pop {pc}
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uart_getc:
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bx =0xfff048ba+1
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asm_memcpy:
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mov r3, r1
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add r3, r3, r2
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asm_memcpy_loop:
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cmp r1, r3
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ldrcc r2, [r1], #4
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strcc r2, [r0], #4
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bcc asm_memcpy_loop
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bx lr
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wdt_disable:
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ldr r1, =0xa0030000
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mov r0, #0x2200
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str r0, [r1]
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bx lr
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