From: Luke Kenneth Casson Leighton Date: Mon, 3 Apr 2023 14:08:14 +0000 (+0100) Subject: clarify example table for elwidth overrides X-Git-Tag: opf_rfc_ls012_v1~153 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=cca6b964f4d3b524fd79b7cd8c1e52b695611ca9;p=libreriscv.git clarify example table for elwidth overrides --- diff --git a/openpower/sv/svp64.mdwn b/openpower/sv/svp64.mdwn index b439f5130..62adce7be 100644 --- a/openpower/sv/svp64.mdwn +++ b/openpower/sv/svp64.mdwn @@ -243,13 +243,17 @@ be as follows. For clarity in the table below: | MSB0: | 0:15 | 16:31 | 32:47 | 48:63 | | LSB0: | 63:48 | 47:32 | 31:16 | 15:0 | |--------|---------|---------|---------|---------| - | GPR(0) | result3 | result2 | result1 | result0 | - | GPR(1) | same | same | same | result4 | + | GPR(0) | same | same | same | same | + | GPR(1) | result3 | result2 | result1 | result0 | + | GPR(2) | same | same | same | result4 | + | GPR(3) | same | same | same | same | + | ... | ... | ... | ... | ... | + | ... | ... | ... | ... | ... | ``` Note that the upper 48 bits of GPR(1) would **not** be modified because the example has VL=5. Thus on "wrapping" - sequential progression from -GPR(0) into GPR(1) - the 5th result modifies +GPR(1) into GPR(2) - the 5th result modifies **only** the bottom 16 LSBs of GPR(1). Hardware Architectural note: to avoid a Read-Modify-Write at the register