| 2016-10-31 10:52:46 |
jeyyej |
description |
pl080 is arm dma controller virtual device.
source code path: hw/dma/pl080.c
I find there are two same dead code in pl080_read and pl080_write,
Here's the code, comments are my opinion:
=========================
240 static uint64_t pl080_read(void *opaque, hwaddr offset,
241 unsigned size)
242 {
243 PL080State *s = (PL080State *)opaque;
244 uint32_t i;
245 uint32_t mask;
246
247 if (offset >= 0xfe0 && offset < 0x1000) {
248 if (s->nchannels == 8) {
249 return pl080_id[(offset - 0xfe0) >> 2];
250 } else {
251 return pl081_id[(offset - 0xfe0) >> 2];
252 }
253 }
254 if (offset >= 0x100 && offset < 0x200) { //// here offset is limited in 0x100~0x200
255 i = (offset & 0xe0) >> 5;
256 if (i >= s->nchannels)
257 goto bad_offset;
258 switch (offset >> 2) { //// then here, offset>>2 is in range 64~128
259 case 0: /* SrcAddr */ //// while the switch case is 0,1,2,3,4,
260 return s->chan[i].src; //// so, NONE of the switch case would be selected !
261 case 1: /* DestAddr */ //// this switch is A DEAD CODE, it is contradictory with if.
262 return s->chan[i].dest;
263 case 2: /* LLI */
264 return s->chan[i].lli;
265 case 3: /* Control */
266 return s->chan[i].ctrl;
267 case 4: /* Configuration */
268 return s->chan[i].conf;
269 default:
270 goto bad_offset;
271 }
272 }
.....................................
=============================================
I guess, switch statement should like this :
switch((offset-0x100)>>2)
{
...
} |
pl080 is arm dma controller virtual device.
source code path: hw/dma/pl080.c
I find there are two same dead code in pl080_read and pl080_write,
Here's the code, comments are my opinion:
=========================
240 static uint64_t pl080_read(void *opaque, hwaddr offset,
241 unsigned size)
242 {
243 PL080State *s = (PL080State *)opaque;
244 uint32_t i;
245 uint32_t mask;
246
247 if (offset >= 0xfe0 && offset < 0x1000) {
248 if (s->nchannels == 8) {
249 return pl080_id[(offset - 0xfe0) >> 2];
250 } else {
251 return pl081_id[(offset - 0xfe0) >> 2];
252 }
253 }
254 if (offset >= 0x100 && offset < 0x200) { //// here offset is limited in 0x100~0x200
255 i = (offset & 0xe0) >> 5;
256 if (i >= s->nchannels)
257 goto bad_offset;
258 switch (offset >> 2) { //// then here, offset>>2 is in range 64~128
259 case 0: /* SrcAddr */ //// while the switch case is 0,1,2,3,4,
260 return s->chan[i].src; //// so, NONE of the switch case would be selected !
261 case 1: /* DestAddr */ //// this switch is A DEAD CODE, it is contradictory with if.
262 return s->chan[i].dest;
263 case 2: /* LLI */
264 return s->chan[i].lli;
265 case 3: /* Control */
266 return s->chan[i].ctrl;
267 case 4: /* Configuration */
268 return s->chan[i].conf;
269 default:
270 goto bad_offset;
271 }
272 }
.....................................
=============================================
I guess, switch statement should like this :
switch((offset-0x100)>>2)
{
...
}
if this DEADCODE is not the author's original purpose,
Then there must be something in logic goes wrong, pl080 have NEVER works correctly ? |
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