From 6857f4ff339826e7c5b2f26cf19d6275208631e6 Mon Sep 17 00:00:00 2001
From: Giovanni Di Sirio <gdisirio@gmail.com>
Date: Fri, 25 Dec 2015 10:13:26 +0000
Subject: USBv1 performance improvements.

git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@8643 35acf78f-673a-0410-8e92-d51de3d6d3f4
---
 os/hal/ports/STM32/LLD/USBv1/usb_lld.c | 56 ++++++++++------------------------
 1 file changed, 16 insertions(+), 40 deletions(-)

(limited to 'os/hal/ports/STM32/LLD')

diff --git a/os/hal/ports/STM32/LLD/USBv1/usb_lld.c b/os/hal/ports/STM32/LLD/USBv1/usb_lld.c
index c06b317bb..05d03f524 100644
--- a/os/hal/ports/STM32/LLD/USBv1/usb_lld.c
+++ b/os/hal/ports/STM32/LLD/USBv1/usb_lld.c
@@ -129,25 +129,17 @@ static uint32_t usb_pm_alloc(USBDriver *usbp, size_t size) {
  */
 static void usb_packet_read_to_buffer(stm32_usb_descriptor_t *udp,
                                       uint8_t *buf, size_t n) {
-  stm32_usb_pma_t *pmap;
-  uint32_t w;
-  size_t i;
+  stm32_usb_pma_t *pmap = USB_ADDR2PTR(udp->RXADDR0);
 
-  pmap = USB_ADDR2PTR(udp->RXADDR0);
+  while (n > 1) {
+    uint32_t w = *pmap++;
+    *buf++ = (uint8_t)w;
+    *buf++ = (uint8_t)(w >> 8);
+    n -= 2;
+  }
 
-  i = 0;
-  w = 0; /* Useless but silences a warning.*/
-  while (i < n) {
-    if ((i & 1) == 0){
-      w = *pmap;
-      *buf = (uint8_t)w;
-      pmap++;
-    }
-    else {
-      *buf = (uint8_t)(w >> 8);
-    }
-    i++;
-    buf++;
+  if (n > 0) {
+    *buf = (uint8_t)*pmap;
   }
 }
 
@@ -164,31 +156,15 @@ static void usb_packet_read_to_buffer(stm32_usb_descriptor_t *udp,
 static void usb_packet_write_from_buffer(stm32_usb_descriptor_t *udp,
                                          const uint8_t *buf,
                                          size_t n) {
+  stm32_usb_pma_t *pmap = USB_ADDR2PTR(udp->TXADDR0);
   uint32_t w;
-  size_t i;
-  stm32_usb_pma_t *pmap;
-
-  pmap = USB_ADDR2PTR(udp->TXADDR0);
-
-  /* Pushing all complete words.*/
-  i = 0;
-  w = 0; /* Useless but silences a warning.*/
-  while (i < n) {
-    if ((i & 1) == 0) {
-      w = (uint32_t)*buf;
-    }
-    else {
-      w |= (uint32_t)*buf << 8;
-      *pmap = (stm32_usb_pma_t)w;
-      pmap++;
-    }
-    i++;
-    buf++;
-  }
+  int i = (int)n;
 
-  /* Remaining byte.*/
-  if ((i & 1) != 0) {
-    *pmap = (stm32_usb_pma_t)w;
+  while (i > 0) {
+    w  = *buf++;
+    w |= *buf++ << 8;
+    *pmap++ = (stm32_usb_pma_t)w;
+    i -= 2;
   }
 }
 
-- 
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