From fda84d7c3802a7a5ad697485fdc3d2ddbee2e21a Mon Sep 17 00:00:00 2001 From: Luke Kenneth Casson Leighton Date: Wed, 18 Sep 2019 08:22:23 +0100 Subject: [PATCH] add elwidth override on MV.X --- simple_v_extension/specification/mv.x.rst | 24 +++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/simple_v_extension/specification/mv.x.rst b/simple_v_extension/specification/mv.x.rst index a921b4aa5..b5ad91830 100644 --- a/simple_v_extension/specification/mv.x.rst +++ b/simple_v_extension/specification/mv.x.rst @@ -30,18 +30,18 @@ swizzle (only active on SV or P48/P64 when SUBVL!=0): Pseudocode for element width part of MV.X: .. code:: python - def mv_x(rd, rs1, funct4): - elwidth = (funct4>>2) & 0x3 - bitwidth = {0:XLEN, 1:8, 2:16, 3:32}[elwidth] # get bits per el - bytewidth = bitwidth / 8 # get bytes per el - for i in range(VL): - addr = (unsigned char *)®s[rs1] - offset = addr + bytewidth # get offset within regfile as SRAM - # TODO, actually, needs to respect rd and rs1 element width, - # here, as well. this pseudocode just illustrates that the - # MV.X operation contains a way to compact the indices into - # less space. - regs[rd] = (unsigned char*)(regs)[offset] + def mv_x(rd, rs1, funct4): + elwidth = (funct4>>2) & 0x3 + bitwidth = {0:XLEN, 1:8, 2:16, 3:32}[elwidth] # get bits per el + bytewidth = bitwidth / 8 # get bytes per el + for i in range(VL): + addr = (unsigned char *)®s[rs1] + offset = addr + bytewidth # get offset within regfile as SRAM + # TODO, actually, needs to respect rd and rs1 element width, + # here, as well. this pseudocode just illustrates that the + # MV.X operation contains a way to compact the indices into + # less space. + regs[rd] = (unsigned char*)(regs)[offset] The idea here is to allow 8-bit indices to be stored inside XLEN-sized registers, such that rather than doing this: -- 2.30.2