On Monday, 4 November 2013 at 11:21:03 UTC, Iain Buclaw wrote:
For the time being, use gcc-4.9-20131013.tar.bz2 snapshot -
that is the
last build I've done here (currently all my time is being used
up on D
2.064).
Feel free to send patches though (see this two line change here:
http://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=02774f2d493655713721ceef4ebfd7d0c8fb1d8d;hp=2043dfcce183f27ffe84a339da8b75aec20d3c33#patch21).
:-)
Ok, I check that later
Meanwhile, a short description of my original problem
I want to send characters of a string to uart
These are member functions of my uart struct. The full source is
https://bitbucket.org/timosi/minlibd/src/540e52150644719682f37900db1c298902e4d8c9/tools/main/uart.d?at=default
// send a byte to the uart
void send(int t) {
while ((sr&0x80)==0)
{
}
dr=t;
}
// send a string or char buffer
void sendtext(const char[] p) {
//if (!p) return; // null pointer test
foreach (c;p) {
//if (c==0) break;
send (c);
}
}
The problem is that send is inlined with -O2 such a way that the
write is optimized outside of the foreach loop and only the last
character is sent.
This works with -O0.
This is the asm
r0 is this, r1 is p and r2 is length of p
151 00ac 10B4 push {r4}
152 00ae 83B0 sub sp, sp, #12
153 00b0 02AB add r3, sp, #8
154 00b2 03E90600 stmdb r3, {r1, r2}
155 00b6 009C ldr r4, [sp]
156 00b8 019A ldr r2, [sp, #4]
157 00ba 4CB1 cbz r4, .L11 zero length test
158 00bc 4368 ldr r3, [r0, #4]
159 00be 1444 add r4, r4, r2
At this point r4 = end address
r2 = p
Foreach begins here
160 .L13:
161 00c0 12F8011B ldrb r1, [r2], #1 get c
162 .L15: First part of send here
163 00c4 0368 ldr r3, [r0] status reg test
164 00c6 1B06 lsls r3, r3, #24 works now!
165 00c8 FCD5 bpl .L15
166 00ca A242 cmp r2, r4 Here in the middle
167 00cc F8D1 bne .L13 the test for end of the loop
168 00ce 4160 str r1, [r0, #4] Write (dr=t) is here,
169 .L11: AFTER the loop
170 00d0 03B0 add sp, sp, #12
171
172 00d2 5DF8044B ldr r4, [sp], #4
173 00d6 7047 bx lr
