[xsrc/trunk]: xsrc/external/mit/xf86-video-suncg14/dist/src add some comments

[macallan <macallan%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/xsrc/rev/de2e32a09228
branches:  trunk
changeset: 10836:de2e32a09228
user:      macallan <macallan%NetBSD.org@localhost>
date:      Fri Dec 24 05:30:07 2021 +0000

description:
add some comments

diffstat:

 external/mit/xf86-video-suncg14/dist/src/cg14.h |  12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diffs (25 lines):

diff -r 55941885910f -r de2e32a09228 external/mit/xf86-video-suncg14/dist/src/cg14.h
--- a/external/mit/xf86-video-suncg14/dist/src/cg14.h   Fri Dec 24 05:22:54 2021 +0000
+++ b/external/mit/xf86-video-suncg14/dist/src/cg14.h   Fri Dec 24 05:30:07 2021 +0000
@@ -135,9 +135,21 @@
        p->queuecount++;
 }
 
+/* convenience macros to hide the complexity involved with talking to SX */
+
+/* 
+ * issue ALU instruction:
+ * sxi(OPCODE, srcA, srcB, dest, count)
+ */
 #define sxi(inst, a, b, d, cnt) write_sx_reg(p, SX_INSTRUCTIONS, inst((a), (b), (d), (cnt)))
+
+/*
+ * issue memory referencing instruction:
+ * sxm(OPCODE, address, start register, count)
+ */
 #define sxm(inst, addr, reg, count) write_sx_io(p, (addr) & ~7, inst((reg), (count), (addr) & 7))
 
+/* hw setup stuff */
 Bool CG14SetupCursor(ScreenPtr);
 Bool CG14InitAccel(ScreenPtr);