From 1b180d2f15e9b726e6e9dde5601f41fa48c1c044 Mon Sep 17 00:00:00 2001
From: Christian Cunningham <cc@localhost>
Date: Mon, 3 Jan 2022 20:10:10 -0800
Subject: Ensured Aligned Mutexes

---
 later/schedule.S | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 later/schedule.S

(limited to 'later/schedule.S')

diff --git a/later/schedule.S b/later/schedule.S
new file mode 100644
index 0000000..1811c7c
--- /dev/null
+++ b/later/schedule.S
@@ -0,0 +1,58 @@
+.section .text
+.globl preserveregs
+preserveregs:
+	str r4,  [r0, #0x10]
+	str r5,  [r0, #0x14]
+	str r6,  [r0, #0x18]
+	str r7,  [r0, #0x1c]
+	str r8,  [r0, #0x20]
+	str r9,  [r0, #0x24]
+	str r10, [r0, #0x28]
+	str r11, [r0, #0x2c]
+	bx lr
+
+.globl restoreregs
+restoreregs:
+	ldr r4,  [r0, #0x10]
+	ldr r5,  [r0, #0x14]
+	ldr r6,  [r0, #0x18]
+	ldr r7,  [r0, #0x1c]
+	ldr r8,  [r0, #0x20]
+	ldr r9,  [r0, #0x24]
+	ldr r10, [r0, #0x28]
+	ldr r11, [r0, #0x2c]
+	bx lr
+
+.globl exetask
+exetask:
+	push {r0, r4, r5, r6, r7, r8, r9, r10, r11, lr}
+	// Restore registers from context switch
+	ldr r4,  [r0, #0x10]
+	ldr r5,  [r0, #0x14]
+	ldr r6,  [r0, #0x18]
+	ldr r7,  [r0, #0x1c]
+	ldr r8,  [r0, #0x20]
+	ldr r9,  [r0, #0x24]
+	ldr r10, [r0, #0x28]
+	ldr r11, [r0, #0x2c]
+
+	// Preserve system stack
+	ldr r1,  =msp
+	str sp, [r1]
+	// Setup task's stack
+	ldr sp, [r0, #0x34]
+	// Switch to task
+	ldr lr, [r0, #0x3c]
+	blx lr
+	// Restore system stack
+	ldr r1, =msp
+	ldr sp, [r1]
+	pop {r0, r4, r5, r6, r7, r8, r9, r10, r11, pc}
+
+.section .data
+msp:
+	.space 4
+.section .data.stacks
+.globl stacks
+stacks:
+	.space 0x100000
-- 
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