From 8bcb552d9755c63d819dc81b901c5b5dc8e3cc8f Mon Sep 17 00:00:00 2001
From: Damien George <damien.p.george@gmail.com>
Date: Wed, 8 May 2019 18:25:18 +1000
Subject: [PATCH] extmod/machine_i2c: Remove need for temporary memory in
writemem() call.
---
extmod/machine_i2c.c | 34 ++++++++++++----------------------
1 file changed, 12 insertions(+), 22 deletions(-)
diff --git a/extmod/machine_i2c.c b/extmod/machine_i2c.c
index 0202fc2bb..63493141c 100644
--- a/extmod/machine_i2c.c
+++ b/extmod/machine_i2c.c
@@ -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[] = {
--
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