rdeaton@ab.com (EATON, ROBERT) (07/18/90)
Hello,
I have been running shy on code space for a z80-based embedded system.
This has forced me to begin converting some of the 'C' code, compiled with the
Intermetrics z80 compiler, to assembly code to save space. If I get creative,
I can reduce the amount of code/function by about 2/3. Just as an example of
how inefficient it is look at the following:
if (pete-> friend == JOE)
000d ED4B 7> | LD BC,pete <----
0011 111900 | LD DE,#25
0014 C5 | PUSH BC <----
0015 E1 | POP HL <----
0016 19 | ADD HL,DE
0017 4E | LD C,(HL)
0018 79 | LD A,C
0019 FE01 | CP #1
001b C2 6> | JP NZ,il_1
See, for example, lines 1, 3 and 4. Why didn't it just load 'pete'
into HL to begin with, instead of loading it into BC and then push/pop into
HL?
As I've been looking at the way it compiles code, a question occurred
to me. Does it do these weird things just in case I use an esoteric 'c'
instruction; as opposed to a simple instructions (whatever that means)? In
other words, does it do these backflips just in case I use a weird 'c'
instruction, that it wouldn't have to do if I used a less complex subset of
'c'?
Maybe a compiler could have two versions. A more efficient version
that can only be used with a subset of 'c' instructions, and a more bulky
version for more complex instructions. I realize this seems picky, but our
code is mostly just 'if,then,else' structures and is very time/space
critical.
Of course this is almost becoming a mute point since no-one uses a
z80 anymore and now we have bigger proms. :-).
Bob Eaton
rdeaton@ab.com
[I have no direct experience with Intermetrics compiler, but it is my
impression that it was written a long time ago. Modern compilers should
have no trouble loading values into the right registers. -John]
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{spdcc | ima | lotus| world}!esegue. Meta-mail to compilers-request@esegue.dwg@bpdsun1.UUCP (David W. Glessner) (07/19/90)
In article <1990Jul17.231931.513@esegue.segue.boston.ma.us> "EATON, ROBERT" <rdeaton@ab.com> writes: > I have been running shy on code space for a z80-based embedded system. >This has forced me to begin converting some of the 'C' code, compiled with >the Intermetrics z80 compiler, to assembly code to save space. Have you looked at a different compiler? Last summer, I asked about Z80 cross compilers for a Sun 3 on comp.lang.c. One person was "VERY! unhappy" with an older version of Intermetrics C for the z80 because: 1) Limited implementation of C 2) High rate of compiler errors 3) Relatively poor ROM support 4) Relatively high price Another claimed that support from Intermetrics was poor. Others suggested Microtec, SDSI, and possibly trying to port gcc. We purchased a source license to HI-TECH Z80 C and ported it to the Sun 3/60. We haven't tested the HI-TECH package extensively, but we're quite pleased so far. Following are the results after coverting some of our Z80 C code from Eco-Soft C (CP/M based) to HI-TECH (Sun based). HI-TECH Eco-Soft ROM space 36718 44831 RAM space 8272 8428 Note that ROM space includes about 8000 lines of assembly files. Here is the assembler output for a test program similar to your example. global _func global _ptr global _noptr psect text ;test.c: 1: struct { char a[25]; char friend; } noptr, *ptr; ;test.c: 2: void func(void) ;test.c: 3: { _func: push iy ;test.c: 4: if (ptr->friend == 1) ; ld iy,(_ptr) ld a,(iy+25) cp 1 jp nz,l3 ;test.c: 5: if (noptr.friend == 1) ; l3: ld a,(_noptr+25) cp 1 jp nz,l2 ;test.c: 6: } l2: pop iy ret psect bss _noptr: defs 26 _ptr: defs 2 psect text end HI-TECH's address is: HI-TECH Software P.O. Box 103, Alderley, QLD, 4051, AUSTRALIA Tel: +61 7 300 5011 Fax: +61 7 300 5246 E-mail: hitech@hitech.ht.oz.au -- David WB9VGB quintro!bpdsun1!dwg@lll-winken.llnl.gov uunet!tiamat!quintro!bpdsun1!dwg -- Send compilers articles to compilers@esegue.segue.boston.ma.us {spdcc | ima | lotus| world}!esegue. Meta-mail to compilers-request@esegue.
mikeh@inmet.inmet.com (07/27/90)
It was recognized several years ago that Intermetrics needed to strengthen
its 8-bit compiler line to compete in the marketplace. This was achieved
when Intermetrics merged with Whitesmiths Ltd. in December 1988, giving
Intermetrics a new line of state-of-the-art 8-bit compilers. These compilers
are as good or better than any found in the marketplace today. Below is the
same source code as posted in the previous note compiled with the Whitesmiths
z80 compiler.
/*********************************************************************/
Here is the equivalent C & asm listing of the Whitesmiths z80 compiler
/*********************************************************************/
.psect _text
; 1 struct { char a[25]; char friend; } noptr, *ptr;
; 2
; 3 void func(void)
; 4 {
_func:
; 5 if(ptr->friend==1);
ld hl,(_ptr)
ld bc,25
add hl,bc
ld a,(hl)
cp 1
; 6 if(noptr.friend==1);
ld a,(_noptr+25)
cp 1
; 7 }
ret
.psect _bss
_ptr:
.byte [2]
_noptr:
.byte [26]
.public _ptr
.public _noptr
.public _func
.end
/*****************************************************************/
Please contact us if you have comments or questions.
Intermetrics Inc.
733 Concord Ave.
Cambridge, MA 02138
617-661-0072
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