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Fix dumb overflow bug

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This commit is contained in:
Steven Robertson 2011-11-11 17:54:33 -05:00
parent eb43b151dc
commit 9ef5363652
1 changed files with 13 additions and 14 deletions
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27
cuburn/code/iter.py
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@ -372,27 +372,20 @@ void iter(
#define SHAB 12
#define SHAW (1<<SHAB)
// These two accumulators, used in write_shmem, hold {density, red} and
// {green, blue} values as packed u16 pairs. The fixed size represents 4,096
// pixels in the accumulator.
__shared__ uint32_t s_acc_dr[SHAW];
__shared__ uint32_t s_acc_gb[SHAW];
// Read from the shm accumulators and write to the global ones.
__device__
void write_shmem_helper(
float4 *acc,
const int glo_base,
const int idx
const int glo_idx,
const int dr,
const int gb
) {
float4 pix = acc[glo_base+idx];
uint32_t dr = s_acc_dr[idx];
float4 pix = acc[glo_idx];
pix.x += (dr & 0xffff) / 255.0f;
pix.w += dr >> 16;
uint32_t gb = s_acc_gb[idx];
pix.y += (gb & 0xffff) / 255.0f;
pix.z += (gb >> 16) / 255.0f;
acc[glo_base+idx] = pix;
acc[glo_idx] = pix;
}
// Read the point log, accumulate in shared memory, and write the results.
@ -417,6 +410,12 @@ write_shmem(
const int tid = threadIdx.x;
const int bid = blockIdx.x;
// These two accumulators, used in write_shmem, hold {density, red} and
// {green, blue} values as packed u16 pairs. The fixed size represents
// 4,096 pixels in the accumulator.
__shared__ uint32_t s_acc_dr[SHAW];
__shared__ uint32_t s_acc_gb[SHAW];
// TODO: doesn't respect SHAW/BS
// TODO: compare generated code with unrolled for-loop
s_acc_dr[tid] = 0;
@ -483,7 +482,7 @@ write_shmem(
if (d == 250) {
atomicSub(s_acc_dr + shr_addr, dr);
atomicSub(s_acc_gb + shr_addr, gb);
write_shmem_helper(acc, glo_base, shr_addr);
write_shmem_helper(acc, glo_base + shr_addr, dr, gb);
}
time += time_step;
}
@ -491,7 +490,7 @@ write_shmem(
__syncthreads();
int idx = tid;
for (int i = 0; i < (SHAW / BS); i++) {
write_shmem_helper(acc, glo_base, idx);
write_shmem_helper(acc, glo_base + idx, s_acc_dr[idx], s_acc_gb[idx]);
idx += BS;
}
}