diff options
| -rw-r--r-- | newlib/libc/sys/amdgcn/write.c | 55 |
1 files changed, 38 insertions, 17 deletions
diff --git a/newlib/libc/sys/amdgcn/write.c b/newlib/libc/sys/amdgcn/write.c index ce5bd360c..9c0d2a968 100644 --- a/newlib/libc/sys/amdgcn/write.c +++ b/newlib/libc/sys/amdgcn/write.c @@ -26,10 +26,14 @@ The next_output counter must be atomically incremented for each print output. Only when the print data is fully written can the - "written" flag be set. */ + "written" flag be set. + + The buffer is circular; the host increments the consumed counter + and clears the written flag as it goes, opening up slots for reuse. + The counters always use absolute numbers. */ struct output { int return_value; - int next_output; + unsigned int next_output; struct printf_data { int written; char msg[128]; @@ -39,7 +43,8 @@ struct output { double dvalue; char text[128]; }; - } queue[1000]; + } queue[1024]; + unsigned int consumed; }; _READ_WRITE_RETURN_TYPE write (int fd, const void *buf, size_t count) @@ -55,33 +60,49 @@ _READ_WRITE_RETURN_TYPE write (int fd, const void *buf, size_t count) struct output *data = (struct output *)kernargs[2]; /* Each output slot allows 256 bytes, so reserve as many as we need. */ - int slot_count = ((count+1)/256)+1; - int index = __atomic_fetch_add (&data->next_output, slot_count, - __ATOMIC_ACQUIRE); + unsigned int slot_count = ((count+1)/256)+1; + unsigned int index = __atomic_fetch_add (&data->next_output, slot_count, + __ATOMIC_ACQUIRE); + + if ((unsigned int)(index + slot_count) < data->consumed) + { + /* Overflow. */ + errno = EFBIG; + return 0; + } + for (int c = count; - c >= 0 && index < 1000; + c >= 0; buf += 256, c -= 256, index++) { + unsigned int slot = index % 1024; + + /* Spinlock while the host catches up. */ + if (index >= 1024) + while (__atomic_load_n (&data->consumed, __ATOMIC_ACQUIRE) + <= (index - 1024)) + asm ("s_sleep 64"); + if (c < 128) { - memcpy (data->queue[index].msg, buf, c); - data->queue[index].msg[c] = '\0'; - data->queue[index].text[0] = '\0'; + memcpy (data->queue[slot].msg, buf, c); + data->queue[slot].msg[c] = '\0'; + data->queue[slot].text[0] = '\0'; } else if (c < 256) { - memcpy (data->queue[index].msg, buf, 128); - memcpy (data->queue[index].text, buf+128, c-128); - data->queue[index].text[c-128] = '\0'; + memcpy (data->queue[slot].msg, buf, 128); + memcpy (data->queue[slot].text, buf+128, c-128); + data->queue[slot].text[c-128] = '\0'; } else { - memcpy (data->queue[index].msg, buf, 128); - memcpy (data->queue[index].text, buf+128, 128); + memcpy (data->queue[slot].msg, buf, 128); + memcpy (data->queue[slot].text, buf+128, 128); } - data->queue[index].type = 3; /* Raw. */ - __atomic_store_n (&data->queue[index].written, 1, __ATOMIC_RELEASE); + data->queue[slot].type = 3; /* Raw. */ + __atomic_store_n (&data->queue[slot].written, 1, __ATOMIC_RELEASE); } return count; |