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controller/Output/pjrcUSB/arm/usb_mem.c

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#include <Lib/USBLib.h>
#include "usb_dev.h"
#include "usb_mem.h"
#define NUM_BUF 30
__attribute__ ((section(".usbbuffers"), used))
//static unsigned char usb_buffer_memory[NUM_BUF * sizeof(usb_packet_t)];
unsigned char usb_buffer_memory[NUM_BUF * sizeof(usb_packet_t)];
static uint32_t usb_buffer_available = 0xFFFFFFFF;
// use bitmask and CLZ instruction to implement fast free list
// http://www.archivum.info/gnu.gcc.help/2006-08/00148/Re-GCC-Inline-Assembly.html
// http://gcc.gnu.org/ml/gcc/2012-06/msg00015.html
// __builtin_clz()
usb_packet_t * usb_malloc(void)
{
unsigned int n, avail;
uint8_t *p;
__disable_irq();
avail = usb_buffer_available;
n = __builtin_clz(avail); // clz = count leading zeros
if (n >= NUM_BUF) {
__enable_irq();
return NULL;
}
//serial_print("malloc:");
//serial_phex(n);
//serial_print("\n");
usb_buffer_available = avail & ~(0x80000000 >> n);
__enable_irq();
p = usb_buffer_memory + (n * sizeof(usb_packet_t));
//serial_print("malloc:");
//serial_phex32((int)p);
//serial_print("\n");
*(uint32_t *)p = 0;
*(uint32_t *)(p + 4) = 0;
return (usb_packet_t *)p;
}
// for the receive endpoints to request memory
extern uint8_t usb_rx_memory_needed;
extern void usb_rx_memory(usb_packet_t *packet);
void usb_free(usb_packet_t *p)
{
unsigned int n, mask;
//serial_print("free:");
n = ((uint8_t *)p - usb_buffer_memory) / sizeof(usb_packet_t);
if (n >= NUM_BUF) return;
//serial_phex(n);
//serial_print("\n");
// if any endpoints are starving for memory to receive
// packets, give this memory to them immediately!
if (usb_rx_memory_needed && usb_configuration) {
//serial_print("give to rx:");
//serial_phex32((int)p);
//serial_print("\n");
usb_rx_memory(p);
return;
}
mask = (0x80000000 >> n);
__disable_irq();
usb_buffer_available |= mask;
__enable_irq();
//serial_print("free:");
//serial_phex32((int)p);
//serial_print("\n");
}