static void esp_do_dma(ESPState *s) { uint32_t len; int to_device; to_device = (s->ti_size < 0); len = s->dma_left; if (s->do_cmd) { DPRINTF("command len %d + %d\n", s->cmdlen, len); s->dma_memory_read(s->dma_opaque, &s->cmdbuf[s->cmdlen], len); s->ti_size = 0; s->cmdlen = 0; s->do_cmd = 0; do_cmd(s, s->cmdbuf); return; } if (s->async_len == 0) { /* Defer until data is available. */ return; } if (len > s->async_len) { len = s->async_len; } if (to_device) { s->dma_memory_read(s->dma_opaque, s->async_buf, len); } else { s->dma_memory_write(s->dma_opaque, s->async_buf, len); } s->dma_left -= len; s->async_buf += len; s->async_len -= len; if (to_device) s->ti_size += len; else s->ti_size -= len; if (s->async_len == 0) { if (to_device) { // ti_size is negative s->current_dev->info->write_data(s->current_dev, 0); } else { s->current_dev->info->read_data(s->current_dev, 0); /* If there is still data to be read from the device then complete the DMA operation immediately. Otherwise defer until the scsi layer has completed. */ if (s->dma_left == 0 && s->ti_size > 0) { esp_dma_done(s); } } } else { /* Partially filled a scsi buffer. Complete immediately. */ esp_dma_done(s); } }