2016-03-01 07:49:26 +00:00
|
|
|
@micropython.asm_thumb
|
|
|
|
def reverse(r0, r1): # bytearray, len(bytearray)
|
|
|
|
add(r4, r0, r1)
|
|
|
|
sub(r4, 1) # end address
|
|
|
|
label(LOOP)
|
|
|
|
ldrb(r5, [r0, 0])
|
|
|
|
ldrb(r6, [r4, 0])
|
|
|
|
strb(r6, [r0, 0])
|
|
|
|
strb(r5, [r4, 0])
|
|
|
|
add(r0, 1)
|
|
|
|
sub(r4, 1)
|
|
|
|
cmp(r4, r0)
|
|
|
|
bpl(LOOP)
|
2017-03-17 16:25:40 +00:00
|
|
|
|
2016-03-01 07:49:26 +00:00
|
|
|
def test():
|
|
|
|
a = bytearray([0, 1, 2, 3]) # even length
|
|
|
|
reverse(a, len(a))
|
|
|
|
print(a)
|
|
|
|
a = bytearray([0, 1, 2, 3, 4]) # odd length
|
|
|
|
reverse(a, len(a))
|
|
|
|
print(a)
|
|
|
|
|
2017-03-17 16:25:40 +00:00
|
|
|
|
|
|
|
# Bit reverse an 8 bit value
|
|
|
|
def rbit8(v):
|
|
|
|
v = (v & 0x0f) << 4 | (v & 0xf0) >> 4
|
|
|
|
v = (v & 0x33) << 2 | (v & 0xcc) >> 2
|
|
|
|
return (v & 0x55) << 1 | (v & 0xaa) >> 1
|
|
|
|
|
|
|
|
# Bit reverse a 16 bit value
|
|
|
|
def rbit16(v):
|
|
|
|
v = (v & 0x00ff) << 8 | (v & 0xff00) >> 8
|
|
|
|
v = (v & 0x0f0f) << 4 | (v & 0xf0f0) >> 4
|
|
|
|
v = (v & 0x3333) << 2 | (v & 0xcccc) >> 2
|
|
|
|
return (v & 0x5555) << 1 | (v & 0xaaaa) >> 1
|
|
|
|
|
|
|
|
# Bit reverse a 32 bit value
|
|
|
|
def rbit32(v):
|
|
|
|
v = (v & 0x0000ffff) << 16 | (v & 0xffff0000) >> 16
|
|
|
|
v = (v & 0x00ff00ff) << 8 | (v & 0xff00ff00) >> 8
|
|
|
|
v = (v & 0x0f0f0f0f) << 4 | (v & 0xf0f0f0f0) >> 4
|
|
|
|
v = (v & 0x33333333) << 2 | (v & 0xcccccccc) >> 2
|
|
|
|
return (v & 0x55555555) << 1 | (v & 0xaaaaaaaa) >> 1
|