From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Tue, 13 Aug 2019 11:00:52 +0000 (+0100)
Subject: add swizzle pseudocode example
X-Git-Tag: convert-csv-opcode-to-binary~4213
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=39b545f681b8e9140418bbf147102a78d7ee7792;p=libreriscv.git

add swizzle pseudocode example
---

diff --git a/simple_v_extension/abridged_spec.mdwn b/simple_v_extension/abridged_spec.mdwn
index 4b52c4897..0bab079dd 100644
--- a/simple_v_extension/abridged_spec.mdwn
+++ b/simple_v_extension/abridged_spec.mdwn
@@ -235,6 +235,21 @@ if this occurs.
 
 [[!inline raw="yes" pages="simple_v_extension/swizzle_table_format" ]]
 
+Pseudocode when SUBVL=4 and swizzle is set on rd:
+
+    # decode the swizzle table entry for rd
+    x = swizzle[0:1]
+    y = swizzle[2:3]
+    z = swizzle[4:5]
+    w = swizzle[6:7]
+
+    # loop on VL: SUBVL loop is unrolled
+    for (i in 0; i < VL; i++)
+        ireg[rd+i*4+x] = OPERATION(ireg[rs1+i*4+0], ireg[rs2+i*4+0])
+        ireg[rd+i*4+y] = OPERATION(ireg[rs1+i*4+1], ireg[rs2+i*4+1])
+        ireg[rd+i*4+z] = OPERATION(ireg[rs1+i*4+2], ireg[rs2+i*4+2])
+        ireg[rd+i*4+w] = OPERATION(ireg[rs1+i*4+3], ireg[rs2+i*4+3])
+
 For more information on swizzling, see the Khronos wiki page
 <https://www.khronos.org/opengl/wiki/Data_Type_(GLSL)#Swizzling>