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#define UART_BASE 0x48000000
#define SPI_BASE 0x48001000
#define GPIO_BASE 0x48002000
#ifndef CFG_STRING
#error Must define CFG_STRING
#endif
.globl _start
_start:
j uart_init
nop
nop
.word cfgstr
uart_init:
// a1 = UART_TX
// a2 = hello_msg_end
// for (a0 = hello_msg_start; a0 != a2; ++ a0){
// while (a3 = TX_READY == 0);
// a3 = *a0
// *a1 = a3
// }
la a0, hello_msg_start
la a2, hello_msg_end
li a1, UART_BASE
uart_loop:
lw a3, 4(a1) // Wait until non-zero (uart can send data).
beqz a3, uart_loop
lb a3, 0(a0) // read the next character in hello_msg
sw a3, 0(a1) // Write the current character.
addi a0, a0, 1 // increment the pointer.
bne a0, a2, uart_loop
gpio_init:
li a0, GPIO_BASE
li t0, 0xFFFF0000
sw t0, 4(a0)
gpio_loop:
// For Red LEDs, increment manually.
li t0, 0x1
sw t0, (a0)
li t0, 0x2
sw t0, (a0)
li t0, 0x4
sw t0, (a0)
li t0, 0x8
sw t0, (a0)
// For Blue and Green LEDs, sample the switches & buttons
lw t0, (a0)
srli t0, t0, 16
andi t0, t0, 0xFF
slli t0, t0, 4
sw t0, (a0)
j gpio_loop
.section .rodata
hello_msg_start:
.incbin "hello_msg.txt"
hello_msg_end:
cfgstr:
.incbin CFG_STRING
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