Macintosh-HW
/
BlueSCSI
mirror of https://github.com/erichelgeson/BlueSCSI.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

Write speed tuning

This commit is contained in:
Glenn Anderson 2022-04-13 16:47:48 -07:00
parent 693ab2a5c0
commit adca34aeb8
1 changed files with 4 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
src/BlueSCSI.cpp
View File

@ -935,14 +935,16 @@ void readDataLoop(uint32_t blockSize, byte* dstptr)
register gpio_reg_map *port_b = PBREG;
register volatile uint32_t *port_a_idr = &(GPIOA->regs->IDR);
REQ_ON();
// Start of the do/while and WAIT are already aligned to 8 bytes.
// Fastest alignment obtained by trial and error.
// Wait loop is within an 8 byte prefetch buffer.
asm("nop");
do {
WAIT_ACK_ACTIVE();
uint32_t ret = port_b->IDR;
REQ_OFF();
*dstptr++ = ~(ret >> 8);
// Move wait loop in to a single 8 byte prefetch buffer
asm("nop.w;nop");
asm("nop;nop;nop");
WAIT_ACK_INACTIVE();
REQ_ON();
// Extra 1 cycle delay