5 files changed, 37 insertions, 13 deletions
diff --git a/02-usart/src/core/clock.c b/02-usart/src/core/clock.c
index d779140..f32cb4e 100644
--- a/02-usart/src/core/clock.c
+++ b/02-usart/src/core/clock.c
@@ -103,4 +103,5 @@ int set_system_clock_src(system_clock_src_t src)
 {
   uint8_t value = RCC.cfg_r & ~0x03;
   RCC.cfg_r = value | src;
+  return 0;
 }
diff --git a/02-usart/src/core/usart.c b/02-usart/src/core/usart.c
index dc15e57..19d982e 100644
--- a/02-usart/src/core/usart.c
+++ b/02-usart/src/core/usart.c
@@ -5,12 +5,12 @@
 
 void set_usart1_clock_src(__IO rcc_t* rcc, usart_clk_src_t usart_clk_src)
 {
-  rcc->ccip_r = rcc->ccip_r & (~0x03) | usart_clk_src;
+  rcc->ccip_r = (rcc->ccip_r & (~0x03)) | usart_clk_src;
 }
 
 void set_usart2_clock_src(__IO rcc_t* rcc, usart_clk_src_t usart_clk_src)
 {
-  rcc->ccip_r = rcc->ccip_r & ~(0x03 << 2) | (usart_clk_src << 2);
+  rcc->ccip_r = (rcc->ccip_r & ~(0x03 << 2)) | (usart_clk_src << 2);
 }
 
 void set_usart2_clock_enabled(__IO rcc_t* rcc, bool enable)
@@ -41,8 +41,6 @@ void usart_set_parity(__IO usart_t* usart, usart_parity_t parity)
 
 void usart_set_enabled(__IO usart_t* usart, usart_enable_t enabled)
 {
-  uint32_t c_r1 = usart->c_r1;
-
   if (!enabled) {
     regset(usart->c_r1, usart_ue, 0);
   } else {
@@ -104,6 +102,7 @@ void usart_printf(__IO usart_t* usart, const char* fmt, ...)
   va_list l;
   union {
     void* ptr;
+    char* str;
     int i;
   } b;
   char buf[128];
@@ -130,6 +129,9 @@ void usart_printf(__IO usart_t* usart, const char* fmt, ...)
           decimalify(b.i, buf);
           usart_transmit_str_sync(usart, buf);
           break;
+        case 's':
+          b.str = va_arg(l, char*);
+          usart_transmit_str_sync(usart, b.str);
       }
       ++ fmt;
     } else {
diff --git a/02-usart/src/main.c b/02-usart/src/main.c
index d26dce4..b050d3e 100644
--- a/02-usart/src/main.c
+++ b/02-usart/src/main.c
@@ -81,9 +81,18 @@ int main()
     for (;;);
   }
 
-  const char* thing = "HELLO DMA!\r\n";
-  regset(USART2.ic_r, usart_tccf, 1);
-  dma_mem2p_initiate_transfer(dma_chan, thing, strlen(thing));
+  // const char* thing = "Good Thing This Works!";
+
+  char* str = halloc(128);
+  strcpy(str, "Hello, Heap!");
+
+  usart_printf(&USART2, "DATA_SEGMENT_START %p\n", &DATA_SEGMENT_START);
+  usart_printf(&USART2, "DATA_SEGMENT_STOP: %p\n", &DATA_SEGMENT_STOP);
+  usart_printf(&USART2, "str at: %p\n", str);
+  usart_printf(&USART2, "str: %s\n", str);
+  // usart_printf(&USART2, "%s\n", thing);
+  // regset(USART2.ic_r, usart_tccf, 1);
+  // dma_mem2p_initiate_transfer(dma_chan, thing, strlen(thing));
 
   __IO gpio_port_t* port_b = enable_gpio(GPIO_PORT_B);
   gpio_output_pin_t pin3 = set_gpio_pin_output(port_b, PIN_3);
diff --git a/02-usart/src/mem.c b/02-usart/src/mem.c
index 0cb9ee4..02d59de 100644
--- a/02-usart/src/mem.c
+++ b/02-usart/src/mem.c
@@ -62,7 +62,7 @@ halloc_node_t* halloc_start;
 void* halloc(size_t size)
 {
   if (!halloc_start) {
-    halloc_start = (halloc_node_t*) DATA_SEGMENT_STOP;
+    halloc_start = (halloc_node_t*) DATA_SEGMENT_STOP_ADDR;
     memset(halloc_start, 0, sizeof(halloc_node_t));
     halloc_start->size = (MAX_HEAP_SIZE / 4) - 1;
   }
@@ -161,20 +161,19 @@ int debug_halloc_assert_consistency(char* error, size_t len)
 {
   halloc_node_t* cur = halloc_node_at_off(0);
   size_t total_size = 0;
-  size_t offset = 0;
   size_t loop_check = 0;
 
   while(1) {
     total_size += cur->size + 1;
 
     halloc_node_t* next = halloc_node_next(cur);
-    if (next == DATA_SEGMENT_STOP + MAX_HEAP_SIZE) {
+    if ((uint8_t*) next == ((uint8_t*)&DATA_SEGMENT_STOP) + MAX_HEAP_SIZE) {
       break;
-    } else if (next > (void*)(DATA_SEGMENT_STOP + MAX_HEAP_SIZE)){
+    } else if ((uint8_t*) next > (uint8_t*)DATA_SEGMENT_STOP_ADDR + MAX_HEAP_SIZE){
       snprintf(
           error, len, "Next node points is out of bounds. %p vs max of %p\n",
           next,
-          (void*)(DATA_SEGMENT_STOP + MAX_HEAP_SIZE));
+          (void*)(DATA_SEGMENT_STOP_ADDR + MAX_HEAP_SIZE));
       return 1;
     }
     cur = next;
@@ -182,7 +181,7 @@ int debug_halloc_assert_consistency(char* error, size_t len)
 
   if (total_size * 4 != MAX_HEAP_SIZE) {
     snprintf(
-        error, len, "Total recorded size is inconsistent. %d vs %d\n",
+        error, len, "Total recorded size is inconsistent. %lu vs %lu\n",
         total_size * 4, MAX_HEAP_SIZE);
     return 1;
   }
diff --git a/02-usart/src/stdlibrepl.c b/02-usart/src/stdlibrepl.c
new file mode 100644
index 0000000..2d9d839
--- /dev/null
+++ b/02-usart/src/stdlibrepl.c
@@ -0,0 +1,13 @@
+/*
+ * Replacement for common stdlib functions that don't exist
+ * on the ARM bare-metal compilation environment.
+ */
+
+#include <stddef.h>
+
+size_t strlen(char* ch)
+{
+  size_t ret = 0;
+  while(*(ch ++) != 0) ++ ret;
+  return ret;
+}