From 93bf62580a68533dc8252b9a2a055c02f34ecb67 Mon Sep 17 00:00:00 2001
From: Christian Cunningham <cc@localhost>
Date: Thu, 24 Mar 2022 09:38:08 -0700
Subject: Modularized

---
 kernel/drivers/uart.S | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)
 create mode 100644 kernel/drivers/uart.S

(limited to 'kernel/drivers/uart.S')

diff --git a/kernel/drivers/uart.S b/kernel/drivers/uart.S
new file mode 100644
index 0000000..38957c2
--- /dev/null
+++ b/kernel/drivers/uart.S
@@ -0,0 +1,53 @@
+.section ".text"
+
+.globl uart_char
+uart_char:
+	mov r2, #0x1000
+	movt r2, #0x3f20
+1:
+	ldr r3, [r2, #24]
+	tst r3, #0b100000
+	bne 1b
+	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}
+1:
+	bl      uart_char
+	ldrb    r0, [r4, #1]!
+	cmp     r0, #0
+	bne 1b
+	pop     {r4, pc}
+
+.globl uart_hex
+uart_hex:
+	push {r4, lr}
+	mov r2, #0x1000
+	movt r2, #0x3f20
+1:
+	ldr r3, [r2, #24]
+	tst r3, #0b100000
+	bne 1b
+	mov r3, #7
+2:
+	mov r1, r0
+	asr r1, r3
+	asr r1, r3
+	asr r1, r3
+	asr r1, r3
+	and r1, #0xf
+	add r1, #0x30
+	cmp r1, #0x3A
+	blt 3f
+	add r1, #7
+3:
+	str r1, [r2]
+	subs r3, #1
+	bge 2b // Jump back to wait for availablilty
+	pop {r4, pc}
-- 
cgit v1.2.1