AES_set_[en|de]crypt_key for ARMv4.

diff --git a/crypto/aes/asm/aes-armv4.pl b/crypto/aes/asm/aes-armv4.pl
index b4049d5d72ea1b88179e66092effabe71a3e1795..69867e74102def3414b67b9cd2fc7b5e566d37e5 100644 (file)
--- a/crypto/aes/asm/aes-armv4.pl
+++ b/crypto/aes/asm/aes-armv4.pl
@@ -10,14 +10,18 @@
 # AES for ARMv4
 
 # January 2007.
 # AES for ARMv4
 
 # January 2007.

-
-# Code uses single 1K S-box and >2 times faster than code compiled
-# with gcc-3.4.1. This is thanks to unique feature of ARMv4 ISA, which
+#
+# Code uses single 1K S-box and is >2 times faster than code generated
+# by gcc-3.4.1. This is thanks to unique feature of ARMv4 ISA, which

 # allows to merge logical or arithmetic operation with shift or rotate
 # in one instruction and emit combined result every cycle. The module
 # is endian-neutral. The performance is ~42 cycles/byte for 128-bit
 # key.
 
 # allows to merge logical or arithmetic operation with shift or rotate
 # in one instruction and emit combined result every cycle. The module
 # is endian-neutral. The performance is ~42 cycles/byte for 128-bit
 # key.
 

+# May 2007.
+#
+# AES_set_[en|de]crypt_key is added.
+

 $s0="r0";
 $s1="r1";
 $s2="r2";
 $s0="r0";
 $s1="r1";
 $s2="r2";


@@ -104,6 +108,43 @@ AES_Te:
 .word  0x65bfbfda, 0xd7e6e631, 0x844242c6, 0xd06868b8
 .word  0x824141c3, 0x299999b0, 0x5a2d2d77, 0x1e0f0f11
 .word  0x7bb0b0cb, 0xa85454fc, 0x6dbbbbd6, 0x2c16163a
 .word  0x65bfbfda, 0xd7e6e631, 0x844242c6, 0xd06868b8
 .word  0x824141c3, 0x299999b0, 0x5a2d2d77, 0x1e0f0f11
 .word  0x7bb0b0cb, 0xa85454fc, 0x6dbbbbd6, 0x2c16163a

+@ Te4[256]
+.byte  0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5
+.byte  0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76
+.byte  0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0
+.byte  0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0
+.byte  0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc
+.byte  0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15
+.byte  0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a
+.byte  0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75
+.byte  0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0
+.byte  0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84
+.byte  0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b
+.byte  0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf
+.byte  0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85
+.byte  0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8
+.byte  0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5
+.byte  0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2
+.byte  0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17
+.byte  0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73
+.byte  0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88
+.byte  0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb
+.byte  0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c
+.byte  0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79
+.byte  0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9
+.byte  0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08
+.byte  0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6
+.byte  0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a
+.byte  0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e
+.byte  0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e
+.byte  0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94
+.byte  0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf
+.byte  0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68
+.byte  0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
+@ rcon[]
+.word  0x01000000, 0x02000000, 0x04000000, 0x08000000
+.word  0x10000000, 0x20000000, 0x40000000, 0x80000000
+.word  0x1B000000, 0x36000000, 0, 0, 0, 0, 0, 0

 .size  AES_Te,.-AES_Te
 
 @ void AES_encrypt(const unsigned char *in, unsigned char *out,
 .size  AES_Te,.-AES_Te
 
 @ void AES_encrypt(const unsigned char *in, unsigned char *out,


@@ -116,7 +157,8 @@ AES_encrypt:
        stmdb   sp!,{r1,r4-r12,lr}
        mov     $rounds,r0              @ inp
        mov     $key,r2
        stmdb   sp!,{r1,r4-r12,lr}
        mov     $rounds,r0              @ inp
        mov     $key,r2

-       sub     $tbl,r3,#1024           @ Te
+       sub     $tbl,r3,#AES_encrypt-AES_Te     @ Te
+

        ldrb    $s0,[$rounds,#3]        @ load input data in endian-neutral
        ldrb    $t1,[$rounds,#2]        @ manner...
        ldrb    $t2,[$rounds,#1]
        ldrb    $s0,[$rounds,#3]        @ load input data in endian-neutral
        ldrb    $t1,[$rounds,#2]        @ manner...
        ldrb    $t2,[$rounds,#1]


@@ -325,6 +367,336 @@ _armv4_AES_encrypt:
        mov     pc,lr                   @ return
 .size  _armv4_AES_encrypt,.-_armv4_AES_encrypt
 
        mov     pc,lr                   @ return
 .size  _armv4_AES_encrypt,.-_armv4_AES_encrypt
 

+.global AES_set_encrypt_key
+.type   AES_set_encrypt_key,%function
+.align 5
+AES_set_encrypt_key:
+       sub     r3,pc,#8                @ AES_set_encrypt_key
+       teq     r0,#0
+       moveq   r0,#-1
+       beq     .Labrt
+       teq     r2,#0
+       moveq   r0,#-1
+       beq     .Labrt
+
+       teq     r1,#128
+       beq     .Lok
+       teq     r1,#192
+       beq     .Lok
+       teq     r1,#256
+       movne   r0,#-1
+       bne     .Labrt
+
+.Lok:  stmdb   sp!,{r4-r12,lr}
+       sub     $tbl,r3,#AES_set_encrypt_key-AES_Te-1024        @ Te4
+
+       mov     $rounds,r0              @ inp
+       mov     lr,r1                   @ bits
+       mov     $key,r2                 @ key
+
+       ldrb    $s0,[$rounds,#3]        @ load input data in endian-neutral
+       ldrb    $t1,[$rounds,#2]        @ manner...
+       ldrb    $t2,[$rounds,#1]
+       ldrb    $t3,[$rounds,#0]
+       orr     $s0,$s0,$t1,lsl#8
+       orr     $s0,$s0,$t2,lsl#16
+       orr     $s0,$s0,$t3,lsl#24
+       ldrb    $s1,[$rounds,#7]
+       ldrb    $t1,[$rounds,#6]
+       ldrb    $t2,[$rounds,#5]
+       ldrb    $t3,[$rounds,#4]
+       orr     $s1,$s1,$t1,lsl#8
+       orr     $s1,$s1,$t2,lsl#16
+       orr     $s1,$s1,$t3,lsl#24
+       ldrb    $s2,[$rounds,#11]
+       ldrb    $t1,[$rounds,#10]
+       ldrb    $t2,[$rounds,#9]
+       ldrb    $t3,[$rounds,#8]
+       orr     $s2,$s2,$t1,lsl#8
+       orr     $s2,$s2,$t2,lsl#16
+       orr     $s2,$s2,$t3,lsl#24
+       ldrb    $s3,[$rounds,#15]
+       ldrb    $t1,[$rounds,#14]
+       ldrb    $t2,[$rounds,#13]
+       ldrb    $t3,[$rounds,#12]
+       orr     $s3,$s3,$t1,lsl#8
+       orr     $s3,$s3,$t2,lsl#16
+       orr     $s3,$s3,$t3,lsl#24
+       str     $s0,[$key],#16
+       str     $s1,[$key,#-12]
+       str     $s2,[$key,#-8]
+       str     $s3,[$key,#-4]
+
+       teq     lr,#128
+       bne     .Lnot128
+       mov     $rounds,#10
+       str     $rounds,[$key,#240-16]
+       add     $t3,$tbl,#256                   @ rcon
+       mov     lr,#255
+
+.L128_loop:
+       and     $t2,lr,$s3,lsr#24
+       and     $i1,lr,$s3,lsr#16
+       and     $i2,lr,$s3,lsr#8
+       and     $i3,lr,$s3
+       ldrb    $t2,[$tbl,$t2]
+       ldrb    $i1,[$tbl,$i1]
+       ldrb    $i2,[$tbl,$i2]
+       ldrb    $i3,[$tbl,$i3]
+       ldr     $t1,[$t3],#4                    @ rcon[i++]
+       orr     $t2,$t2,$i1,lsl#24
+       orr     $t2,$t2,$i2,lsl#16
+       orr     $t2,$t2,$i3,lsl#8
+       eor     $t2,$t2,$t1
+       eor     $s0,$s0,$t2                     @ rk[4]=rk[0]^...
+       eor     $s1,$s1,$s0                     @ rk[5]=rk[1]^rk[4]
+       eor     $s2,$s2,$s1                     @ rk[6]=rk[2]^rk[5]
+       eor     $s3,$s3,$s2                     @ rk[7]=rk[3]^rk[6]
+       str     $s0,[$key],#16
+       str     $s1,[$key,#-12]
+       str     $s2,[$key,#-8]
+       str     $s3,[$key,#-4]
+
+       subs    $rounds,$rounds,#1
+       bne     .L128_loop
+       sub     r2,$key,#176
+       b       .Ldone
+
+.Lnot128:
+       ldrb    $i2,[$rounds,#19]
+       ldrb    $t1,[$rounds,#18]
+       ldrb    $t2,[$rounds,#17]
+       ldrb    $t3,[$rounds,#16]
+       orr     $i2,$i2,$t1,lsl#8
+       orr     $i2,$i2,$t2,lsl#16
+       orr     $i2,$i2,$t3,lsl#24
+       ldrb    $i3,[$rounds,#23]
+       ldrb    $t1,[$rounds,#22]
+       ldrb    $t2,[$rounds,#21]
+       ldrb    $t3,[$rounds,#20]
+       orr     $i3,$i3,$t1,lsl#8
+       orr     $i3,$i3,$t2,lsl#16
+       orr     $i3,$i3,$t3,lsl#24
+       str     $i2,[$key],#8
+       str     $i3,[$key,#-4]
+
+       teq     lr,#192
+       bne     .Lnot192
+       mov     $rounds,#12
+       str     $rounds,[$key,#240-24]
+       add     $t3,$tbl,#256                   @ rcon
+       mov     lr,#255
+       mov     $rounds,#8
+
+.L192_loop:
+       and     $t2,lr,$i3,lsr#24
+       and     $i1,lr,$i3,lsr#16
+       and     $i2,lr,$i3,lsr#8
+       and     $i3,lr,$i3
+       ldrb    $t2,[$tbl,$t2]
+       ldrb    $i1,[$tbl,$i1]
+       ldrb    $i2,[$tbl,$i2]
+       ldrb    $i3,[$tbl,$i3]
+       ldr     $t1,[$t3],#4                    @ rcon[i++]
+       orr     $t2,$t2,$i1,lsl#24
+       orr     $t2,$t2,$i2,lsl#16
+       orr     $t2,$t2,$i3,lsl#8
+       eor     $i3,$t2,$t1
+       eor     $s0,$s0,$i3                     @ rk[6]=rk[0]^...
+       eor     $s1,$s1,$s0                     @ rk[7]=rk[1]^rk[6]
+       eor     $s2,$s2,$s1                     @ rk[8]=rk[2]^rk[7]
+       eor     $s3,$s3,$s2                     @ rk[9]=rk[3]^rk[8]
+       str     $s0,[$key],#24
+       str     $s1,[$key,#-20]
+       str     $s2,[$key,#-16]
+       str     $s3,[$key,#-12]
+
+       subs    $rounds,$rounds,#1
+       subeq   r2,$key,#216
+       beq     .Ldone
+
+       ldr     $i1,[$key,#-32]
+       ldr     $i2,[$key,#-28]
+       eor     $i1,$i1,$s3                     @ rk[10]=rk[4]^rk[9]
+       eor     $i3,$i2,$i1                     @ rk[11]=rk[5]^rk[10]
+       str     $i1,[$key,#-8]
+       str     $i3,[$key,#-4]
+       b       .L192_loop
+
+.Lnot192:
+       ldrb    $i2,[$rounds,#27]
+       ldrb    $t1,[$rounds,#26]
+       ldrb    $t2,[$rounds,#25]
+       ldrb    $t3,[$rounds,#24]
+       orr     $i2,$i2,$t1,lsl#8
+       orr     $i2,$i2,$t2,lsl#16
+       orr     $i2,$i2,$t3,lsl#24
+       ldrb    $i3,[$rounds,#31]
+       ldrb    $t1,[$rounds,#30]
+       ldrb    $t2,[$rounds,#29]
+       ldrb    $t3,[$rounds,#28]
+       orr     $i3,$i3,$t1,lsl#8
+       orr     $i3,$i3,$t2,lsl#16
+       orr     $i3,$i3,$t3,lsl#24
+       str     $i2,[$key],#8
+       str     $i3,[$key,#-4]
+
+       mov     $rounds,#14
+       str     $rounds,[$key,#240-32]
+       add     $t3,$tbl,#256                   @ rcon
+       mov     lr,#255
+       mov     $rounds,#7
+
+.L256_loop:
+       and     $t2,lr,$i3,lsr#24
+       and     $i1,lr,$i3,lsr#16
+       and     $i2,lr,$i3,lsr#8
+       and     $i3,lr,$i3
+       ldrb    $t2,[$tbl,$t2]
+       ldrb    $i1,[$tbl,$i1]
+       ldrb    $i2,[$tbl,$i2]
+       ldrb    $i3,[$tbl,$i3]
+       ldr     $t1,[$t3],#4                    @ rcon[i++]
+       orr     $t2,$t2,$i1,lsl#24
+       orr     $t2,$t2,$i2,lsl#16
+       orr     $t2,$t2,$i3,lsl#8
+       eor     $i3,$t2,$t1
+       eor     $s0,$s0,$i3                     @ rk[8]=rk[0]^...
+       eor     $s1,$s1,$s0                     @ rk[9]=rk[1]^rk[8]
+       eor     $s2,$s2,$s1                     @ rk[10]=rk[2]^rk[9]
+       eor     $s3,$s3,$s2                     @ rk[11]=rk[3]^rk[10]
+       str     $s0,[$key],#32
+       str     $s1,[$key,#-28]
+       str     $s2,[$key,#-24]
+       str     $s3,[$key,#-20]
+
+       subs    $rounds,$rounds,#1
+       subeq   r2,$key,#256
+       beq     .Ldone
+
+       and     $t2,lr,$s3
+       and     $i1,lr,$s3,lsr#8
+       and     $i2,lr,$s3,lsr#16
+       and     $i3,lr,$s3,lsr#24
+       ldrb    $t2,[$tbl,$t2]
+       ldrb    $i1,[$tbl,$i1]
+       ldrb    $i2,[$tbl,$i2]
+       ldrb    $i3,[$tbl,$i3]
+       orr     $t2,$t2,$i1,lsl#8
+       orr     $t2,$t2,$i2,lsl#16
+       orr     $t2,$t2,$i3,lsl#24
+
+       ldr     $t1,[$key,#-48]
+       ldr     $i1,[$key,#-44]
+       ldr     $i2,[$key,#-40]
+       ldr     $i3,[$key,#-36]
+       eor     $t1,$t1,$t2                     @ rk[12]=rk[4]^...
+       eor     $i1,$i1,$t1                     @ rk[13]=rk[5]^rk[12]
+       eor     $i2,$i2,$i1                     @ rk[14]=rk[6]^rk[13]
+       eor     $i3,$i3,$i2                     @ rk[15]=rk[7]^rk[14]
+       str     $t1,[$key,#-16]
+       str     $i1,[$key,#-12]
+       str     $i2,[$key,#-8]
+       str     $i3,[$key,#-4]
+       b       .L256_loop
+
+.Ldone:        mov     r0,#0
+       ldmia   sp!,{r4-r12,lr}
+.Labrt:        tst     lr,#1
+       moveq   pc,lr                   @ be binary compatible with V4, yet
+       bx      lr                      @ interoperable with Thumb ISA:-)
+.size  AES_set_encrypt_key,.-AES_set_encrypt_key
+
+.global AES_set_decrypt_key
+.type   AES_set_decrypt_key,%function
+.align 5
+AES_set_decrypt_key:
+       str     lr,[sp,#-4]!            @ push lr
+       bl      AES_set_encrypt_key
+       teq     r0,#0
+       ldrne   lr,[sp],#4              @ pop lr
+       bne     .Labrt
+
+       stmdb   sp!,{r4-r12}
+
+       ldr     $rounds,[r2,#240]       @ AES_set_encrypt_key preserves r2,
+       mov     $key,r2                 @ which is AES_KEY *key
+       mov     $i1,r2
+       add     $i2,r2,$rounds,lsl#4
+
+.Linv: ldr     $s0,[$i1]
+       ldr     $s1,[$i1,#4]
+       ldr     $s2,[$i1,#8]
+       ldr     $s3,[$i1,#12]
+       ldr     $t1,[$i2]
+       ldr     $t2,[$i2,#4]
+       ldr     $t3,[$i2,#8]
+       ldr     $i3,[$i2,#12]
+       str     $s0,[$i2],#-16
+       str     $s1,[$i2,#16+4]
+       str     $s2,[$i2,#16+8]
+       str     $s3,[$i2,#16+12]
+       str     $t1,[$i1],#16
+       str     $t2,[$i1,#-12]
+       str     $t3,[$i1,#-8]
+       str     $i3,[$i1,#-4]
+       teq     $i1,$i2
+       bne     .Linv
+___
+$mask80=$i1;
+$mask1b=$i2;
+$mask7f=$i3;
+$code.=<<___;
+       ldr     $s0,[$key,#16]!         @ prefetch tp1
+       mov     $mask80,#0x80
+       mov     $mask1b,#0x1b
+       orr     $mask80,$mask80,#0x8000
+       orr     $mask1b,$mask1b,#0x1b00
+       orr     $mask80,$mask80,$mask80,lsl#16
+       orr     $mask1b,$mask1b,$mask1b,lsl#16
+       sub     $rounds,$rounds,#1
+       mvn     $mask7f,$mask80
+       mov     $rounds,$rounds,lsl#2   @ (rounds-1)*4
+
+.Lmix: and     $t1,$s0,$mask80
+       and     $s1,$s0,$mask7f
+       sub     $t1,$t1,$t1,lsr#7
+       and     $t1,$t1,$mask1b
+       eor     $s1,$t1,$s1,lsl#1       @ tp2
+
+       and     $t1,$s1,$mask80
+       and     $s2,$s1,$mask7f
+       sub     $t1,$t1,$t1,lsr#7
+       and     $t1,$t1,$mask1b
+       eor     $s2,$t1,$s2,lsl#1       @ tp4
+
+       and     $t1,$s2,$mask80
+       and     $s3,$s2,$mask7f
+       sub     $t1,$t1,$t1,lsr#7
+       and     $t1,$t1,$mask1b
+       eor     $s3,$t1,$s3,lsl#1       @ tp8
+
+       eor     $t1,$s1,$s2
+       eor     $t2,$s0,$s3             @ tp9
+       eor     $t1,$t1,$s3             @ tpe
+       eor     $t1,$t1,$s1,ror#24
+       eor     $t1,$t1,$t2,ror#24      @ ^= ROTATE(tpb=tp9^tp2,8)
+       eor     $t1,$t1,$s2,ror#16
+       eor     $t1,$t1,$t2,ror#16      @ ^= ROTATE(tpd=tp9^tp4,16)
+       eor     $t1,$t1,$t2,ror#8       @ ^= ROTATE(tp9,24)
+
+       ldr     $s0,[$key,#4]           @ prefetch tp1
+       str     $t1,[$key],#4
+       subs    $rounds,$rounds,#1
+       bne     .Lmix
+
+       mov     r0,#0
+       ldmia   sp!,{r4-r12,lr}
+       tst     lr,#1
+       moveq   pc,lr                   @ be binary compatible with V4, yet
+       bx      lr                      @ interoperable with Thumb ISA:-)
+.size  AES_set_decrypt_key,.-AES_set_decrypt_key
+

 .type  AES_Td,%object
 .align 5
 AES_Td:
 .type  AES_Td,%object
 .align 5
 AES_Td:


@@ -392,7 +764,7 @@ AES_Td:
 .word  0x161dc372, 0xbce2250c, 0x283c498b, 0xff0d9541
 .word  0x39a80171, 0x080cb3de, 0xd8b4e49c, 0x6456c190
 .word  0x7bcb8461, 0xd532b670, 0x486c5c74, 0xd0b85742
 .word  0x161dc372, 0xbce2250c, 0x283c498b, 0xff0d9541
 .word  0x39a80171, 0x080cb3de, 0xd8b4e49c, 0x6456c190
 .word  0x7bcb8461, 0xd532b670, 0x486c5c74, 0xd0b85742

-
+@ Td4[256]

 .byte  0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38
 .byte  0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb
 .byte  0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87
 .byte  0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38
 .byte  0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb
 .byte  0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87


@@ -437,7 +809,8 @@ AES_decrypt:
        stmdb   sp!,{r1,r4-r12,lr}
        mov     $rounds,r0              @ inp
        mov     $key,r2
        stmdb   sp!,{r1,r4-r12,lr}
        mov     $rounds,r0              @ inp
        mov     $key,r2

-       sub     $tbl,r3,#1280           @ Td
+       sub     $tbl,r3,#AES_decrypt-AES_Td             @ Td
+

        ldrb    $s0,[$rounds,#3]        @ load input data in endian-neutral
        ldrb    $t1,[$rounds,#2]        @ manner...
        ldrb    $t2,[$rounds,#1]
        ldrb    $s0,[$rounds,#3]        @ load input data in endian-neutral
        ldrb    $t1,[$rounds,#2]        @ manner...
        ldrb    $t2,[$rounds,#1]