Add subroutine for printing hexadecimal word

10 files changed, 69 insertions, 14 deletions

diff --git a/Makefile b/hexedit/Makefile
index 3529884..95f49ae 100644
--- a/Makefile
+++ b/hexedit/Makefile
@@ -3,7 +3,7 @@ all: build
 build: echo.uf2
 
 echo.uf2: echo.elf
-	./elf2uf2 echo.elf echo.uf2
+	../elf/elf2uf2 echo.elf echo.uf2
 
 objects = main.o xosc.o clocks.o gpio.o uart.o
 
diff --git a/clocks.s b/hexedit/clocks.s
index 83bc9ff..83bc9ff 100644
--- a/clocks.s
+++ b/hexedit/clocks.s
diff --git a/gpio.s b/hexedit/gpio.s
index 32e2c37..32e2c37 100644
--- a/gpio.s
+++ b/hexedit/gpio.s
diff --git a/hexedit/hexedit.s b/hexedit/hexedit.s
new file mode 100644
index 0000000..0bc03a9
--- /dev/null
+++ b/hexedit/hexedit.s
@@ -0,0 +1,25 @@
+.syntax unified
+.cpu cortex-m0plus
+.thumb
+
+.type hexedit, %function
+.global hexedit
+
+hexedit:
+  ldr r2, =0x20000100
+  movs r1, 0
+getchar:
+  bl uart_recv
+  cmp r0, 'g
+  beq stop
+  subs r0, '0 // The ASCII char '0'
+  bmi next
+  lsls r1, 4
+  adds r1, r0
+  b getchar
+next:
+  ldr r0, [r2, 0]
+  adds r2, 4
+  b hexedit
+stop:
+  b 0x20000100
diff --git a/main.s b/hexedit/main.s
index 5e294d4..5e294d4 100644
--- a/main.s
+++ b/hexedit/main.s
diff --git a/pico_ram_only.ld b/hexedit/pico_ram_only.ld
index eb2450e..eb2450e 100644
--- a/pico_ram_only.ld
+++ b/hexedit/pico_ram_only.ld
diff --git a/uart.s b/hexedit/uart.s
index 19a2882..9804e53 100644
--- a/uart.s
+++ b/hexedit/uart.s
@@ -62,14 +62,12 @@ setup_uart:
 
 uart_send:
   ldr r1, =UART0_BASE
+  movs r3, 0b1 << 5 // TX FIFO full
 1:
   ldr r2, [r1, UARTFR_OFST]
-  movs r3, 0b1 << 5 // TX FIFO full
   tst r2, r3
   bne 1b
-  movs r2, 0xff
-  ands r0, r2
-  str r0, [r1, UARTDR_OFST]
+  strb r0, [r1, UARTDR_OFST]
   bx lr
 
 .type uart_recv, %function
@@ -77,10 +75,42 @@ uart_send:
 
 uart_recv:
   ldr r1, =UART0_BASE
+  movs r3, 0b1 << 4 // RX FIFO empty
 1:
   ldr r2, [r1, UARTFR_OFST]
-  movs r3, 0b1 << 4 // RX FIFO empty
   tst r2, r3
   bne 1b
-  ldr r0, [r1, UARTDR_OFST]
+  ldrb r0, [r1, UARTDR_OFST]
   bx lr
+
+.type send_hex, %function
+.global send_hex
+
+send_hex:
+  push {lr}
+  movs r4, r0
+  movs r0, '0
+  bl uart_send
+  movs r0, 'x
+  bl uart_send
+  movs r5, 8 // eight nibbles in a word
+0:
+  movs r0, 28 // rotate left 4
+  rors r4, r0
+  movs r0, 0xF // lowest nibble mask
+  ands r0, r4
+  cmp r0, 0x9 // number or letter?
+  bhi 1f
+  adds r0, '0
+  b 2f
+1:
+  adds r0, 'A - 0xA
+2:
+  bl uart_send
+  subs r5, 1
+  bne 0b
+  movs r0, '\r
+  bl uart_send
+  movs r0, '\n
+  bl uart_send
+  pop {pc}
diff --git a/xosc.s b/hexedit/xosc.s
index 883200f..63760da 100644
--- a/xosc.s
+++ b/hexedit/xosc.s
@@ -12,7 +12,7 @@
 
 start_xosc:
   ldr r1, =XOSC_BASE
-  movs r0, 47 // startup delay = 47 for 12Mhz crystal
+  movs r0, 47 // startup delay for 12Mhz crystal
   str r0, [r1, STARTUP_OFST]
   ldr r0, =0x00fabaa0 // enable
   str r0, [r1, CTRL_OFST]
diff --git a/blink.s b/misc/blink.s
index 5b65eb4..46e6eff 100644
--- a/blink.s
+++ b/misc/blink.s
@@ -22,7 +22,7 @@ setup_led:
   str r0, [r1, 0]
   ldr r1, =SIO_BASE
   movs r0, 1
-  lsls r0, r0, 25 // GPIO 25 (LED) output enable
+  lsls r0, 25 // GPIO 25 (LED) output enable
   str r0, [r1, GPIO_OE_SET_OFST]
   bx lr
 
@@ -79,7 +79,7 @@ on_then_off:
   bl delay_quick
   str r2, [r1, GPIO_OUT_XOR_OFST]
   bl delay_quick
-  subs r0, r0, 1
+  subs r0, 1
   bne on_then_off
 done:
   pop {pc}
diff --git a/pll.s b/misc/pll.s
index bab31f2..faeacb1 100644
--- a/pll.s
+++ b/misc/pll.s
@@ -37,9 +37,9 @@ start_pll:
   // set pl_sys post dividers to 12 (6 * 2)
   ldr r1, =PLL_SYS_BASE
   movs r0, 6 // POSTDIV1 = 6
-  lsls r0, r0, 4
-  adds r0, r0, 2 // POSTDIV2 = 2
-  lsls r0, r0, 12
+  lsls r0, 4
+  adds r0, 2 // POSTDIV2 = 2
+  lsls r0, 12
   str r0, [r1, PRIM_OFST]
   // turn on main power and VCO
   ldr r1, =(PLL_SYS_BASE + ATOMIC_CLEAR)
@@ -49,7 +49,7 @@ start_pll:
   ldr r1, =PLL_SYS_BASE
 vco_lock:
   ldr r2, [r1, CS_OFST]
-  lsrs r2, r2, 31
+  lsrs r2, 31
   beq vco_lock
   // turn on post divider power
   ldr r1, =(PLL_SYS_BASE + ATOMIC_CLEAR)