IORD and IOWR, the question is easy:)

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The IORD and IOWR macros treat the offset as a four byte word offset. Here are some examples:

IOWR(0, 4, 1234). -> writes 1234 to base 0 + word offset 4 (byte address 0 + 4x4= 16)

IORD(12, 2) -> reads from base 12 + word offset 2 (byte address 12+2x4 = 20)

In general the byte offset is 'base + offset x 4'. The access size is always 4 bytes which is why I don't recommend using IORD and IOWR and use the 8/16/32DIRECT ones instead which always use byte offsets.

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I understand, thank you so much.

If the word to read is a pio, for example with 8 bit, it makes sense to calculate an offset?

Where can I study these things?

thank you so much.