cvw/testsBP/fpga-test-sdc/test-sdc.asm
Ross Thompson 3a9bc1e8c1 Updated the fpga bios code to emulate the same behavior as qemu's bootloader and it also copies
the flash card to dram.
Fixed latch issue in the sd card reader.
2021-09-26 13:22:23 -05:00

98 lines
1.1 KiB
NASM

#PERIOD = 22000000
PERIOD = 20
.section .init
.global _start
.type _start, @function
_start:
# Initialize global pointer
.option push
.option norelax
1:auipc gp, %pcrel_hi(__global_pointer$)
addi gp, gp, %pcrel_lo(1b)
.option pop
li x1, 0
li x2, 0
li x4, 0
li x5, 0
li x6, 0
li x7, 0
li x8, 0
li x9, 0
li x10, 0
li x11, 0
li x12, 0
li x13, 0
li x14, 0
li x15, 0
li x16, 0
li x17, 0
li x18, 0
li x19, 0
li x20, 0
li x21, 0
li x22, 0
li x23, 0
li x24, 0
li x25, 0
li x26, 0
li x27, 0
li x28, 0
li x29, 0
li x30, 0
li x31, 0
# set the stack pointer to the top of memory - 8 bytes (pointer size)
li sp, 0x87FFFFF8
li a0, 0x20000000
li a1, 0x80000000
li a2, 2
jal ra, copyFlash
# now toggle led so we know the copy completed.
# write to gpio
li t2, 0xFF
la t3, 0x1001200C
li t4, 5
loop:
# delay
li t0, PERIOD/2
delay1:
addi t0, t0, -1
bge t0, x0, delay1
sw t2, 0x0(t3)
li t0, PERIOD/2
delay2:
addi t0, t0, -1
bge t0, x0, delay2
sw x0, 0x0(t3)
addi t4, t4, -1
bgt t4, x0, loop
jal ra, _halt
.section .text
.global _halt
.type _halt, @function
_halt:
li gp, 1
li a0, 0
ecall
j _halt