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How-to-Program with Griffy-C
- Griffy-C syntax Ing. Claudio Mucci
ARCES University of Bologna
Data Flow Graph
A
B
C
D E
F
„
+
-
G
|
H
I
+
&
L
M
+
C-Described Data Flow
Graph features:
– Node functionality is
described by a C-level
operators (e.g. +, -, >>,
<<, &, |, …)
– Each edge is described by
a Single Assignment
Variables
OUT = ((A+B)+(C-D)) + ((C-D) & (E|F));
ARCES University of Bologna
C-Described DFG
A
B
C
D E
+
F
-
Inputs: A,B,C,D,E,F
Output: OUT
|
Manually-Dismantled Code:
G
H
I
+
&
L
M
+
OUT = ((A+B)+(C-D)) + ((C-D) & (E|F));
G = A + B;
H = C - D;
I = E | F;
L = G + H;
M = I & H;
OUT = L + M;
ARCES University of Bologna
Manual Dismantling
Bad dismantling
Good dismantling
ARCES University of Bologna
PiCoGAop Description
#pragma fpga NAME OPCODE DELAY NOUTS NINS OUTS INS
{
// Local variables declaration:
[static] unsigned/signed int/short int/char <vars>;
// Local attribute declaration:
#pragma attrib <vars> [SIZE=<dim>, SAT]
[function description]
}
#pragma end
ARCES University of Bologna
Griffy-C Description – Supported operators
„
Function description:
– Add, Sub (+, -)
– Shift (<<, >>)
– Bitwise and, Bitwise or, Bitwise xor,
Bitwise not (&, |, ^, ~)
– Compare (==, !=, >, <, >=, <=)
– Conditional assignment (cond ? if_true : if_false )
– Concatenation (dest = src1 # src2 ;)
– LUT programming (dest = src @ 0x[LUT] ;)
ƒ Example: and6i = input @ 0x1;
ARCES University of Bologna
Griffy-C Variable Attributes
„
„
#pragma attrib:
– SIZE=nbits (nbits < original size)
– SAT
ƒ var_name = data1 [+/-] data2;
ƒ var_name(overflow) Æ if var_name is signed
ƒ var_name(carryout) Æ if var_name is unsigned
Variable resizing:
– resized_var = original_var;
– resized_var = original_var >> step;
ARCES University of Bologna
Example
#pragma fpga absolute_difference 0x11 4 1 2 dataout datain1 datain2
{
unsigned char diff1, diff2;
char cond;
#pragma attrib cond SIZE=1
diff1 = datain1 - datain2;
diff2 = datain2 - datain1;
-
-
cond = diff1 < 0;
dataout = cond ? diff2 : diff1;
}
#pragma end
MUX
ARCES University of Bologna
How-to-Program with Griffy-C
- Griffy-C environment -
ARCES University of Bologna
Algorithm Implementation Flow on the
PiCoGA
Griffy-C
„
„
„
„
„
DFG description
Assembly-like code
Single-Assignment
variables
Bit-level setting of
variable size
Intermediate
Representation for
Advanced C-Compiler
„
„
„
Pipelined DFG
Library-based
C-operands
mapping
Routing-only
operations
detection
Library-based Synthesis
ARCES University of Bologna
Place & Route
„
Placement
– Pipeline stages fitting
into one or more rows
– Regular placement
based on C-driven
library elements
„
Routing
– Based on the opensource VPR-router
(University of Toronto)
ARCES University of Bologna
XiRouter
Global inputs (from Register File)
„
Syntax:
xipr_opt function_name
Global outputs (to Register File)
ARCES University of Bologna
Griffy-C Æ PiCoGA
„ Syntax:
FastGriffy [options] filename.c
Main options:
[-v2] – Verbose mode
[-noplace] – Disable placement (only first-tentative placement)
[-ps] – Provide the PostScript-file of the pipelined DFG
Other options: type FastGriffy without arguments
Emulation Function
Griffy-C Description
FastGriffy
Filename_fpga.[ch]
Configuration Bits
ARCES University of Bologna
XiRisc Algorithm Development
Environment
ARCES University of Bologna
XiRisc C-compiler
„ GNU
GCC toolchain retargeted for XiRisc
„ Tools:
– Compiler: build [options] filename.c
ƒ Main options: +debug, +64
ƒ HELP Æ build
ƒ Output in test.exe/test.gdb
ƒ Disassembled executable: test.read
– Debugger: ddd test.gdb &
ARCES University of Bologna
XiRisc-DDD Debugger
ARCES University of Bologna
XiRisc Profiler
„ Single
Datapath Profiler:
– SingleProf_fast <filename>
(without .c extension)
„ XiRisc
Profiler:
– DoubleProf_fast <filename>
(without .c extension)
„ Outputs:
filename[_double].profas
filename[_double].profc
ARCES University of Bologna
C-code with PiCoGAop
„ PGAOP
instance:
– pga_name (args list);
„ PGALOAD
instance:
– pga_load_df_<pga_name> ();
„ PGAFREE
instance:
– pga_free_<pga_name> ();
ARCES University of Bologna
Esercitazione Laboratorio
„
„
emacs/vi Æ Scrittura codice C & Griffy-C
xhost +
ssh/rsh griffy (192.168.1.130)
setenv DISPLAY cad<xx>:0.0
source ~griffy/griffy.tcsh
FastGriffy –ps –v2 <filename.c>
„
„
build +debug <filename_fpga.c>
ddd test.gdb &
„
DoubleProf_fast <filename_fpga>
„
„
„
„
– xipr_opt <func_name> Æ Place & Route
– gv <func_name>
Æ Pipelined DFG
– target sim
– load test.gdb
ARCES University of Bologna
Esercizio
Realizzazione di un sommatore di 8 elementi, ciascuno
rappresentato da 8 bit, sull'architettura riconfigurabile XiRisc.
• Scrivere il codice C relativo all'implementazione tradizionale
(puramente software)
•Effettuare mapping su PiCoGA del sommatore, stimando la
latenza
• Riscrivere il codice C con l'opportuno inserimento delle pgaop
• Fornire una stima dello speed-up ottenibile
Ipotesi semplificativa:
Non considerare l'overflow sui risultati intermedi
ARCES University of Bologna
Account Laboratorio CAD
„ Per
ricevere l’account per l’accesso alla
saletta CAD occorre riempire il form
all’indirizzo:
http://tori.ing.unibo.it/l3l/guerrieri.php
„ Per
oggi account temporanei
ARCES University of Bologna