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decode_length returns negative value -> 172b

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Dennis Ranke
2022-09-18 22:36:31 +02:00
parent ad731c2e75
commit 612084a5bf
1 changed files with 10 additions and 12 deletions
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22
asm_unpackers/unpack_armv6m.S
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@@ -49,7 +49,7 @@ upkr_unpack:
1: 1:
bl upkr_decode_length bl upkr_decode_length
subs r3, r6, r4 adds r3, r4, #1
beq .Lend beq .Lend
2: 2:
@@ -57,10 +57,11 @@ upkr_unpack:
bl upkr_decode_length bl upkr_decode_length
.Lcopy_loop: .Lcopy_loop:
ldrb r5, [r0, r3] ldrb r5, [r0, r3]
.Lstore:
strb r5, [r0] strb r5, [r0]
adds r0, r0, #1 adds r0, r0, #1
subs r4, r4, #1 adds r4, r4, #1
bne .Lcopy_loop blt .Lcopy_loop
b .Lloop b .Lloop
.Ldata: .Ldata:
@@ -71,29 +72,26 @@ upkr_unpack:
adcs r5, r5, r5 adcs r5, r5, r5
lsrs r4, r5, #8 lsrs r4, r5, #8
beq .Ldata_loop beq .Ldata_loop
b .Lstore
strb r5, [r0]
adds r0, r0, #1
b .Lloop
.Lend: .Lend:
add sp, sp, #FRAME_SIZE add sp, sp, #FRAME_SIZE
pop { r4, r5, r6, r7, pc } pop { r4, r5, r6, r7, pc }
.type upkr_decode_length, %function .type upkr_decode_length, %function
// r0 .. length tmp (saved) // r0 .. -length tmp (saved)
// r1 .. // r1 ..
// r2 .. // r2 ..
// r3 .. // r3 ..
// r4 .. length (returned) // r4 .. -length (returned)
// r5 .. context index (saved) // r5 .. context index (saved)
// r6 .. (saved) // r6 .. (saved)
// r7 .. // r7 ..
upkr_decode_length: upkr_decode_length:
push { r0, r5, r6, lr } push { r0, r5, r6, lr }
movs r4, #1
movs r0, #0 movs r0, #0
subs r4, r0, #1
.Lbit_loop: .Lbit_loop:
adds r5, r5, #1 adds r5, r5, #1
bl upkr_decode_bit bl upkr_decode_bit
@@ -102,12 +100,12 @@ upkr_decode_length:
adds r5, r5, #1 adds r5, r5, #1
bl upkr_decode_bit bl upkr_decode_bit
beq 2f beq 2f
orrs r0, r0, r4 adds r0, r0, r4
2: 2:
lsls r4, r4, #1 lsls r4, r4, #1
b .Lbit_loop b .Lbit_loop
1: 1:
orrs r4, r4, r0 adds r4, r4, r0
pop { r0, r5, r6, pc } pop { r0, r5, r6, pc }