From 20fa8584e31d55b7f2953f917adcc190adab236f Mon Sep 17 00:00:00 2001
From: Christian Cunningham <cc@localhost>
Date: Tue, 31 Aug 2021 08:31:10 -0700
Subject: Initial Commit

---
 src/uart.S | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 src/uart.S

(limited to 'src/uart.S')

diff --git a/src/uart.S b/src/uart.S
new file mode 100644
index 0000000..bd98bac
--- /dev/null
+++ b/src/uart.S
@@ -0,0 +1,46 @@
+.section ".text"
+
+.globl uart_init
+uart_init:
+    //*UART0_IMSC = 1 << 4;
+    mov r2, #0x1038
+    movt r2, #0x3F20
+    mov r3, #0b10000
+    str r3, [r2]
+    //*IRQ_ENABLE2 = 1 << 25;
+    mov r2, #0xB214
+    movt r2, #0x3F00
+    mov r3, #0
+    movt r3, #0b1000000000
+    str r3, [r2]
+    //*GPU_INTERRUPTS_ROUTING = 0x00;
+    mov r2, #0x000C
+    movt r2, #0x4000
+    eor r3, r3
+    str r3, [r2]
+    bx lr
+
+.globl uart_char
+uart_char:
+    mov r2, #0x1000
+    movt r2, #0x3f20
+uart_char.loop:
+    ldr r3, [r2, #24]
+    tst r3, #0b100000
+    bne uart_char.loop
+    str r0, [r2]
+    bx lr
+
+.globl uart_string
+uart_string:
+    push    {r4, lr}
+    mov     r4, r0
+    ldrb    r0, [r0]
+    cmp     r0, #0
+    popeq   {r4, pc}
+uart_string.loop:
+    bl      uart_char
+    ldrb    r0, [r4, #1]!
+    cmp     r0, #0
+    bne     uart_string.loop
+    pop     {r4, pc}
-- 
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