core/cortex-m0/curve25519: Import fast curve25519 implementation

Import finely tuned curve25519 implementation from
https://munacl.cryptojedi.org/curve25519-cortexm0.shtml
(http://munacl.cryptojedi.org/data/curve25519-cortexm0-20150813.tar.bz2)
which is released in the public domain for some files, CC0 for others.

This is a plain copy (only doing a pass of dos2unix conversion
and removing trailing tabs/spaces), later patches integrate the
code with the rest of the EC code.

BRANCH=none
BUG=b:62813194
TEST=None (see next patch)

Change-Id: Ibd394d031433c31d4755a880b0e8d74b63540fbf
Reviewed-on: https://chromium-review.googlesource.com/540961
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>

1 files changed, 199 insertions, 0 deletions

diff --git a/core/cortex-m0/curve25519/cortex_m0_mpy121666.s b/core/cortex-m0/curve25519/cortex_m0_mpy121666.s
new file mode 100644
index 0000000000..8e74dd0265
--- /dev/null
+++ b/core/cortex-m0/curve25519/cortex_m0_mpy121666.s
@@ -0,0 +1,199 @@
+// Implementation of multiplication of an fe25519 bit value with the curve constant 121666.
+//
+// B. Haase, Endress + Hauser Conducta GmbH & Ko. KG
+// public domain.
+//
+// gnu assembler format.
+//
+// Generated and tested with C++ functions in the test subdirectory.
+//
+// ATTENTION:
+// Not yet tested on target hardware.
+
+
+	.cpu cortex-m0
+	.fpu softvfp
+	.eabi_attribute 20, 1
+	.eabi_attribute 21, 1
+	.eabi_attribute 23, 3
+	.eabi_attribute 24, 1
+	.eabi_attribute 25, 1
+	.eabi_attribute 26, 1
+	.eabi_attribute 30, 2
+	.eabi_attribute 34, 0
+	.eabi_attribute 18, 4
+	.code	16
+
+	.file	"cortex_m0_reduce25519.s"
+
+	.text
+	.align	2
+
+	.global	fe25519_mpyWith121666_asm
+	.code	16
+	.thumb_func
+	.type	fe25519_mpyWith121666_asm, %function
+
+fe25519_mpyWith121666_asm:
+    push {r4,r5,r6,r7,r14}
+    ldr r7,__label_for_immediate_56130
+    ldr r2,[r1,#28]
+    lsl r5,r2,#16
+    lsr r6,r2,#16
+    lsr r3,r2,#16
+    uxth r2,r2
+    mul r2,r7
+    mul r3,r7
+    add r5,r2
+    mov r2,#0
+    adc r6,r2
+    lsl r2,r3,#16
+    lsr r3,r3,#16
+    add r5,r2
+    adc r6,r3
+    lsl r2,r5,#1
+    lsr r2,r2,#1
+    str r2,[r0,#28]
+    lsr r5,r5,#31
+    lsl r6,r6,#1
+    orr r5,r6
+    mov r6,#19
+    mul r5,r6
+    mov r6,#0
+    ldr r2,[r1,#0]
+    lsl r3,r2,#16
+    lsr r4,r2,#16
+    add r5,r3
+    adc r6,r4
+    lsr r3,r2,#16
+    uxth r2,r2
+    mul r2,r7
+    mul r3,r7
+    add r5,r2
+    mov r2,#0
+    adc r6,r2
+    lsl r2,r3,#16
+    lsr r3,r3,#16
+    add r5,r2
+    adc r6,r3
+    str r5,[r0,#0]
+    mov r5,#0
+    ldr r2,[r1,#4]
+    lsl r3,r2,#16
+    lsr r4,r2,#16
+    add r6,r3
+    adc r5,r4
+    lsr r3,r2,#16
+    uxth r2,r2
+    mul r2,r7
+    mul r3,r7
+    add r6,r2
+    mov r2,#0
+    adc r5,r2
+    lsl r2,r3,#16
+    lsr r3,r3,#16
+    add r6,r2
+    adc r5,r3
+    str r6,[r0,#4]
+    mov r6,#0
+    ldr r2,[r1,#8]
+    lsl r3,r2,#16
+    lsr r4,r2,#16
+    add r5,r3
+    adc r6,r4
+    lsr r3,r2,#16
+    uxth r2,r2
+    mul r2,r7
+    mul r3,r7
+    add r5,r2
+    mov r2,#0
+    adc r6,r2
+    lsl r2,r3,#16
+    lsr r3,r3,#16
+    add r5,r2
+    adc r6,r3
+    str r5,[r0,#8]
+    mov r5,#0
+    ldr r2,[r1,#12]
+    lsl r3,r2,#16
+    lsr r4,r2,#16
+    add r6,r3
+    adc r5,r4
+    lsr r3,r2,#16
+    uxth r2,r2
+    mul r2,r7
+    mul r3,r7
+    add r6,r2
+    mov r2,#0
+    adc r5,r2
+    lsl r2,r3,#16
+    lsr r3,r3,#16
+    add r6,r2
+    adc r5,r3
+    str r6,[r0,#12]
+    mov r6,#0
+    ldr r2,[r1,#16]
+    lsl r3,r2,#16
+    lsr r4,r2,#16
+    add r5,r3
+    adc r6,r4
+    lsr r3,r2,#16
+    uxth r2,r2
+    mul r2,r7
+    mul r3,r7
+    add r5,r2
+    mov r2,#0
+    adc r6,r2
+    lsl r2,r3,#16
+    lsr r3,r3,#16
+    add r5,r2
+    adc r6,r3
+    str r5,[r0,#16]
+    mov r5,#0
+    ldr r2,[r1,#20]
+    lsl r3,r2,#16
+    lsr r4,r2,#16
+    add r6,r3
+    adc r5,r4
+    lsr r3,r2,#16
+    uxth r2,r2
+    mul r2,r7
+    mul r3,r7
+    add r6,r2
+    mov r2,#0
+    adc r5,r2
+    lsl r2,r3,#16
+    lsr r3,r3,#16
+    add r6,r2
+    adc r5,r3
+    str r6,[r0,#20]
+    mov r6,#0
+    ldr r2,[r1,#24]
+    lsl r3,r2,#16
+    lsr r4,r2,#16
+    add r5,r3
+    adc r6,r4
+    lsr r3,r2,#16
+    uxth r2,r2
+    mul r2,r7
+    mul r3,r7
+    add r5,r2
+    mov r2,#0
+    adc r6,r2
+    lsl r2,r3,#16
+    lsr r3,r3,#16
+    add r5,r2
+    adc r6,r3
+    str r5,[r0,#24]
+    mov r5,#0
+    ldr r2,[r0,#28]
+    add r6,r2
+    str r6,[r0,#28]
+    pop {r4,r5,r6,r7,r15}
+
+	.align	2
+__label_for_immediate_56130:
+	.word 56130
+
+	.size	fe25519_mpyWith121666_asm, .-fe25519_mpyWith121666_asm
+