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extmod/machine_i2c: Remove need for temporary memory in writemem() call.

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This commit is contained in:
Damien George 2019-05-08 18:25:18 +10:00
parent 647b27d028
commit 8bcb552d97
1 changed files with 12 additions and 22 deletions
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34
extmod/machine_i2c.c
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@ -496,35 +496,25 @@ STATIC int read_mem(mp_obj_t self_in, uint16_t addr, uint32_t memaddr, uint8_t a
return mp_machine_i2c_readfrom(self, addr, buf, len, true);
}
#define MAX_MEMADDR_SIZE (4)
#define BUF_STACK_SIZE (12)
STATIC int write_mem(mp_obj_t self_in, uint16_t addr, uint32_t memaddr, uint8_t addrsize, const uint8_t *buf, size_t len) {
mp_obj_base_t *self = (mp_obj_base_t*)MP_OBJ_TO_PTR(self_in);
// need some memory to create the buffer to send; try to use stack if possible
uint8_t buf2_stack[MAX_MEMADDR_SIZE + BUF_STACK_SIZE];
uint8_t *buf2;
size_t buf2_alloc = 0;
if (len <= BUF_STACK_SIZE) {
buf2 = buf2_stack;
} else {
buf2_alloc = MAX_MEMADDR_SIZE + len;
buf2 = m_new(uint8_t, buf2_alloc);
}
// create the buffer to send
// Create buffer with memory address
size_t memaddr_len = 0;
uint8_t memaddr_buf[4];
for (int16_t i = addrsize - 8; i >= 0; i -= 8) {
buf2[memaddr_len++] = memaddr >> i;
memaddr_buf[memaddr_len++] = memaddr >> i;
}
memcpy(buf2 + memaddr_len, buf, len);
int ret = mp_machine_i2c_writeto(self, addr, buf2, memaddr_len + len, true);
if (buf2_alloc != 0) {
m_del(uint8_t, buf2, buf2_alloc);
}
return ret;
// Create partial write buffers
mp_machine_i2c_buf_t bufs[2] = {
{.len = memaddr_len, .buf = memaddr_buf},
{.len = len, .buf = (uint8_t*)buf},
};
// Do I2C transfer
mp_machine_i2c_p_t *i2c_p = (mp_machine_i2c_p_t*)self->type->protocol;
return i2c_p->transfer(self, addr, 2, bufs, MP_MACHINE_I2C_FLAG_STOP);
}
STATIC const mp_arg_t machine_i2c_mem_allowed_args[] = {