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author | Silvan Jegen <s.jegen@gmail.com> | 2019-07-22 23:04:17 +0200 |
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committer | Silvan Jegen <s.jegen@gmail.com> | 2019-07-22 23:04:17 +0200 |
commit | f5e284223d25ee5beab98de95cd74e3ac72a39a6 (patch) | |
tree | 33d6b2b3a0e5fa5b1d0b3094108bac78bd84bda0 /software/first/delay.S | |
parent | 4bc2e5141c68e82f2f6d7c8f71051fe93dd96d18 (diff) |
Implement first superblink version
Diffstat (limited to 'software/first/delay.S')
-rw-r--r-- | software/first/delay.S | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/software/first/delay.S b/software/first/delay.S new file mode 100644 index 0000000..cb49ba1 --- /dev/null +++ b/software/first/delay.S @@ -0,0 +1,26 @@ +.section .text +.align 2 +.global delay +.include "memory_map.inc" + + +# a0 is delay in milliseconds argument + +delay: + addi sp, sp, -16 # Allocate stack frame + sw ra, 12(sp) # save return address to the stack + + li t0, MTIME # load the timer register + lw t1, 0(t0) # load value of the timer + + li t2, MTIME_FREQUENCY # get clock freq (approx.) + mul t2, t2, a0 # multiply milliseconds with freq + add t2, t1, t2 # target mtime is now in t2 + +1: + lw t1, 0(t0) # load value of the timer + blt t1, t2, 1b # keep looping until target mtime has been reached + + lw ra, 12(sp) # load return address + addi sp, sp, 16 # deallocate stack frame + ret |