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-rw-r--r--3/3_data_formats/main.c16
-rw-r--r--3/3_data_formats/mstore/mstore.c6
-rw-r--r--3/3_data_formats/mstore/mstore.s21
-rw-r--r--3/4_register_and_addresses/main.c27
-rw-r--r--3/5_arith_and_logic/movq_size.s16
-rw-r--r--3/5_arith_and_logic/remdiv.c12
-rw-r--r--3/5_arith_and_logic/remdiv.s38
-rw-r--r--3/5_arith_and_logic/reverse_assemble.c23
-rw-r--r--3/5_arith_and_logic/sarl.c11
-rw-r--r--3/5_arith_and_logic/store_uprod.c11
-rw-r--r--3/5_arith_and_logic/store_uprod.s27
-rw-r--r--3/5_arith_and_logic/xorq_size.c5
-rw-r--r--3/5_arith_and_logic/xorq_size.s16
-rw-r--r--3/6_control/20_op_bias.c10
-rw-r--r--3/6_control/21_test_cmov.c20
-rw-r--r--3/6_control/22_loop.c51
-rw-r--r--3/6_control/23_reverse_engineer_loop.c28
-rw-r--r--3/6_control/24_while_loop.c24
-rw-r--r--3/6_control/absdiff_goto.c39
-rw-r--r--3/6_control/comp.c36
-rw-r--r--3/6_control/cond.c6
-rw-r--r--3/6_control/missing.c13
22 files changed, 456 insertions, 0 deletions
diff --git a/3/3_data_formats/main.c b/3/3_data_formats/main.c
new file mode 100644
index 0000000..7fac153
--- /dev/null
+++ b/3/3_data_formats/main.c
@@ -0,0 +1,16 @@
+#include <stdio.h>
+
+void multstore(long, long, long *);
+
+long mult2(long a, long b) {
+ long s = a * b;
+ return s;
+}
+
+int main() {
+ long d;
+ multstore(2, 3, &d);
+ printf("2 * 3 --> %ld\n", d);
+ return 0;
+}
+
diff --git a/3/3_data_formats/mstore/mstore.c b/3/3_data_formats/mstore/mstore.c
new file mode 100644
index 0000000..cdcf205
--- /dev/null
+++ b/3/3_data_formats/mstore/mstore.c
@@ -0,0 +1,6 @@
+long mult2(long, long);
+
+void multstore(long x, long y, long *dest) {
+ long t = mult2(x, y);
+ *dest = t;
+}
diff --git a/3/3_data_formats/mstore/mstore.s b/3/3_data_formats/mstore/mstore.s
new file mode 100644
index 0000000..e215a2b
--- /dev/null
+++ b/3/3_data_formats/mstore/mstore.s
@@ -0,0 +1,21 @@
+ .file "mstore.c"
+ .text
+ .globl multstore
+ .type multstore, @function
+multstore:
+.LFB0:
+ .cfi_startproc
+ pushq %rbx
+ .cfi_def_cfa_offset 16
+ .cfi_offset 3, -16
+ movq %rdx, %rbx
+ call mult2@PLT
+ movq %rax, (%rbx)
+ popq %rbx
+ .cfi_def_cfa_offset 8
+ ret
+ .cfi_endproc
+.LFE0:
+ .size multstore, .-multstore
+ .ident "GCC: (GNU) 12.3.0"
+ .section .note.GNU-stack,"",@progbits
diff --git a/3/4_register_and_addresses/main.c b/3/4_register_and_addresses/main.c
new file mode 100644
index 0000000..f767ee6
--- /dev/null
+++ b/3/4_register_and_addresses/main.c
@@ -0,0 +1,27 @@
+#include <stdio.h>
+
+void decode1(long *xp, long *yp, long *zp) {
+ long x = *xp;
+ long y = *yp;
+ long z = *zp;
+
+ *yp = x;
+ *zp = y;
+ *xp = z;
+}
+
+long scale(long x, long y, long z) {
+ long t = x + 4 * y + 12 * z;
+ return t;
+}
+
+long scale3(long x, long y, long z) {
+ long t = 10 * y + z + x * y;
+ return t;
+}
+
+int main(void) {
+ char c = 0xC0;
+ int x = (int) c;
+ printf("%d", x);
+}
diff --git a/3/5_arith_and_logic/movq_size.s b/3/5_arith_and_logic/movq_size.s
new file mode 100644
index 0000000..3d525df
--- /dev/null
+++ b/3/5_arith_and_logic/movq_size.s
@@ -0,0 +1,16 @@
+ .file "xorq_size.c"
+ .text
+ .section .text.startup,"ax",@progbits
+ .p2align 4
+ .globl main
+ .type main, @function
+main:
+.LFB0:
+ .cfi_startproc
+ movl $0, %eax
+ ret
+ .cfi_endproc
+.LFE0:
+ .size main, .-main
+ .ident "GCC: (GNU) 12.3.0"
+ .section .note.GNU-stack,"",@progbits
diff --git a/3/5_arith_and_logic/remdiv.c b/3/5_arith_and_logic/remdiv.c
new file mode 100644
index 0000000..8d3c957
--- /dev/null
+++ b/3/5_arith_and_logic/remdiv.c
@@ -0,0 +1,12 @@
+#include <stdio.h>
+
+void remdiv(long x, long y, long *qp, long *rp) {
+ long q = x/y;
+ long r = x%y;
+ *qp = q;
+ *rp = r;
+}
+
+int main() {
+ remdiv(0,0,0,0);
+}
diff --git a/3/5_arith_and_logic/remdiv.s b/3/5_arith_and_logic/remdiv.s
new file mode 100644
index 0000000..61c66df
--- /dev/null
+++ b/3/5_arith_and_logic/remdiv.s
@@ -0,0 +1,38 @@
+ .file "remdiv.c"
+ .text
+ .globl remdiv
+ .type remdiv, @function
+remdiv:
+.LFB23:
+ .cfi_startproc
+ movq %rdi, %rax
+ movq %rdx, %r8
+ xorq %rdx, %rdx
+ divq %rsi
+ movq %rax, (%r8)
+ movq %rdx, (%rcx)
+ ret
+ .cfi_endproc
+.LFE23:
+ .size remdiv, .-remdiv
+ .globl main
+ .type main, @function
+main:
+.LFB24:
+ .cfi_startproc
+ subq $8, %rsp
+ .cfi_def_cfa_offset 16
+ movl $0, %ecx
+ movl $0, %edx
+ movl $0, %esi
+ movl $0, %edi
+ call remdiv@PLT
+ movl $0, %eax
+ addq $8, %rsp
+ .cfi_def_cfa_offset 8
+ ret
+ .cfi_endproc
+.LFE24:
+ .size main, .-main
+ .ident "GCC: (GNU) 12.3.0"
+ .section .note.GNU-stack,"",@progbits
diff --git a/3/5_arith_and_logic/reverse_assemble.c b/3/5_arith_and_logic/reverse_assemble.c
new file mode 100644
index 0000000..6413f98
--- /dev/null
+++ b/3/5_arith_and_logic/reverse_assemble.c
@@ -0,0 +1,23 @@
+#include <stdio.h>
+
+/*
+ * x in %rdi, y in %rsi, z in %rdx
+ * arith3:
+ * orq %rsi, %rdx
+ * sarq $9, %rdx
+ * notq %rdx
+ * movq %rdx, %bax <------- what is this register??
+ * subq %rsi, %rbx
+ * ret
+ */
+short arith3(short x, short y, short z) {
+ short p1 = z | y;
+ short p2 = p1>>9;
+ short p3 = ~p2;
+ short p4 = p3;
+ return p4;
+}
+
+int main() {
+
+}
diff --git a/3/5_arith_and_logic/sarl.c b/3/5_arith_and_logic/sarl.c
new file mode 100644
index 0000000..51e6305
--- /dev/null
+++ b/3/5_arith_and_logic/sarl.c
@@ -0,0 +1,11 @@
+#include <stdio.h>
+
+long shift_left4_rightn(long x, long n) {
+ x <<= 4;
+ x >>= n;
+ return x;
+}
+
+int main() {
+ printf("%d", shift_left4_rightn(15, 5));
+}
diff --git a/3/5_arith_and_logic/store_uprod.c b/3/5_arith_and_logic/store_uprod.c
new file mode 100644
index 0000000..0009e09
--- /dev/null
+++ b/3/5_arith_and_logic/store_uprod.c
@@ -0,0 +1,11 @@
+#include <inttypes.h>
+
+typedef unsigned __int128 uint128_t;
+
+void store_uprod(uint128_t *dest, uint64_t x, uint64_t y) {
+ *dest = x * (uint128_t) y;
+}
+
+int main() {
+ return 0;
+}
diff --git a/3/5_arith_and_logic/store_uprod.s b/3/5_arith_and_logic/store_uprod.s
new file mode 100644
index 0000000..a099e77
--- /dev/null
+++ b/3/5_arith_and_logic/store_uprod.s
@@ -0,0 +1,27 @@
+ .file "store_uprod.c"
+ .text
+ .globl store_uprod
+ .type store_uprod, @function
+store_uprod:
+.LFB0:
+ .cfi_startproc
+ movq %rsi, %rax
+ mulq %rdx
+ movq %rax, (%rdi)
+ movq %rdx, 8(%rdi)
+ ret
+ .cfi_endproc
+.LFE0:
+ .size store_uprod, .-store_uprod
+ .globl main
+ .type main, @function
+main:
+.LFB1:
+ .cfi_startproc
+ movl $0, %eax
+ ret
+ .cfi_endproc
+.LFE1:
+ .size main, .-main
+ .ident "GCC: (GNU) 12.3.0"
+ .section .note.GNU-stack,"",@progbits
diff --git a/3/5_arith_and_logic/xorq_size.c b/3/5_arith_and_logic/xorq_size.c
new file mode 100644
index 0000000..5751590
--- /dev/null
+++ b/3/5_arith_and_logic/xorq_size.c
@@ -0,0 +1,5 @@
+int main() {
+ int x = 5;
+ x ^= x;
+ return 0;
+}
diff --git a/3/5_arith_and_logic/xorq_size.s b/3/5_arith_and_logic/xorq_size.s
new file mode 100644
index 0000000..ed88d9a
--- /dev/null
+++ b/3/5_arith_and_logic/xorq_size.s
@@ -0,0 +1,16 @@
+ .file "xorq_size.c"
+ .text
+ .section .text.startup,"ax",@progbits
+ .p2align 4
+ .globl main
+ .type main, @function
+main:
+.LFB0:
+ .cfi_startproc
+ xorl %eax, %eax
+ ret
+ .cfi_endproc
+.LFE0:
+ .size main, .-main
+ .ident "GCC: (GNU) 12.3.0"
+ .section .note.GNU-stack,"",@progbits
diff --git a/3/6_control/20_op_bias.c b/3/6_control/20_op_bias.c
new file mode 100644
index 0000000..b071eb9
--- /dev/null
+++ b/3/6_control/20_op_bias.c
@@ -0,0 +1,10 @@
+#define OP <
+
+// x <- %rdi
+// %rbx <- 15 + (x), bias to round towards zero
+// ZF, SF <- %rdi & %rdi, check if pos or neg
+// %rbx <- x if x >= 0, set to unbiased if pos
+// %rbx <- %rbx >> 4, divide by 16
+short arith(short x) {
+ return x / 16;
+}
diff --git a/3/6_control/21_test_cmov.c b/3/6_control/21_test_cmov.c
new file mode 100644
index 0000000..a90d178
--- /dev/null
+++ b/3/6_control/21_test_cmov.c
@@ -0,0 +1,20 @@
+#include <stdio.h>
+
+// Remember that jumps flip conditionals
+// Also testq rdi rdi and jge test if the sign bit is set
+short test(short x, short y) {
+ short val = 12 + y;
+ if (x < 0) {
+ if (x >= y)
+ val = x | y;
+ else
+ val = x * y;
+ } else if (y >= 10) {
+ val = x / y;
+ }
+ return val;
+}
+
+int main(void) {
+ return 0;
+}
diff --git a/3/6_control/22_loop.c b/3/6_control/22_loop.c
new file mode 100644
index 0000000..73c7710
--- /dev/null
+++ b/3/6_control/22_loop.c
@@ -0,0 +1,51 @@
+#include <limits.h>
+#include <stdint.h>
+#include <stdio.h>
+// do
+// body
+// while (test);
+//
+// loop:
+// body
+// t = test;
+// if (t)
+// goto loop;
+
+typedef int64_t fact_t;
+
+long fact_do(long n)
+{
+ long result = 1;
+ do {
+ result *= n;
+ n = n-1;
+ } while (n > 1);
+ return result;
+}
+
+int tmult_ok(fact_t x, fact_t y)
+{
+ fact_t p = x*y;
+ return !x || p/x == y;
+}
+
+fact_t fact_do_int(size_t n)
+{
+ fact_t result = 1;
+ do {
+ if (tmult_ok(result, n)) {
+ result *= n;
+ n = n-1;
+ } else {
+ printf("would overflow this iter, n=%ld\n", n);
+ n = 0;
+ }
+ } while (n > 1);
+ return result;
+}
+
+int main(void) {
+ size_t f = 20;
+ printf("result: %ld, max: %ld, less: %d", fact_do_int(f), INT64_MAX, fact_do_int(f) < INT64_MAX);
+ return 0;
+}
diff --git a/3/6_control/23_reverse_engineer_loop.c b/3/6_control/23_reverse_engineer_loop.c
new file mode 100644
index 0000000..922b317
--- /dev/null
+++ b/3/6_control/23_reverse_engineer_loop.c
@@ -0,0 +1,28 @@
+short dw_loop(short x)
+{
+ short y = x/9;
+ short *p = &x;
+ short n = 4*x;
+ do {
+ x += y;
+ (*p) += 5;
+ n += 2;
+ } while (n > 0);
+ return x;
+}
+
+// x in %rdi
+// dw_loop:
+// movq %rdi, %rdx # %rbx <- x
+// movq %rdi, %rcx # %rcx <- x
+// idivq $9, %rcx # %rcx (y) <- x / 9
+// leaq (,%rdi,4), %rdx # %rdx (n) <- x * 4
+// .L2:
+// leaq 5(%rbx,%rcx), %rcx # %rbx (x) <- 5 + %rbx (x) + %rcx (y)
+// subq $1, %rdx # %rdx (n) <- n - 1
+// testq %rdx, %rdx # n > 0 ?
+// jg .L2 # if n > 0, goto .L2
+// rep; ret
+//
+// A. x in rbx, y in rcx, n in rdx
+// B. The pointer is never used besides incrementing the value at the address. So it is replaced by a incrementing instruction in the loop.
diff --git a/3/6_control/24_while_loop.c b/3/6_control/24_while_loop.c
new file mode 100644
index 0000000..a3367fc
--- /dev/null
+++ b/3/6_control/24_while_loop.c
@@ -0,0 +1,24 @@
+// while (test)
+// body
+//
+// goto test;
+// loop:
+// body;
+// test:
+// t = test;
+// if (t)
+// goto loop;
+
+short loop_while(short a, short b)
+{
+ short result = ;
+ while () {
+ result = ;
+ a = ;
+ }
+ return result;
+}
+
+int main(void) {
+ return 0;
+}
diff --git a/3/6_control/absdiff_goto.c b/3/6_control/absdiff_goto.c
new file mode 100644
index 0000000..dfcb3be
--- /dev/null
+++ b/3/6_control/absdiff_goto.c
@@ -0,0 +1,39 @@
+#include <stdio.h>
+
+// if (!t)
+// goto false;
+// then-
+// goto done;
+// false:
+// else-
+// goto done;
+// done:
+// ...
+long gotodiff_se(long x, long y)
+{
+ long result;
+ if (x >= y)
+ goto x_ge_y;
+ lt_cnt++;
+ result = y - x;
+ return result;
+
+x_get_y:
+ ge_cnt++;
+ result = x - y;
+ return result;
+}
+
+long gotodiff_se_alternate(long x, long y)
+{
+ long result;
+ if (x < y)
+ goto x_le_y;
+ ge_cnt++;
+ result = x - y;
+ return result;
+x_le_y:
+ lt_cnt++;
+ result = y - x;
+ return result;
+}
diff --git a/3/6_control/comp.c b/3/6_control/comp.c
new file mode 100644
index 0000000..beba875
--- /dev/null
+++ b/3/6_control/comp.c
@@ -0,0 +1,36 @@
+#include <stdio.h>
+
+typedef char data_t;
+
+#define COMP <=
+
+// a in rdx, b in rsi
+//
+// cmpl %esi, %edi (Compare long (double word, or 4 bytes). (a - b) )
+// setl %al (set lower? %rax return value)
+//
+// COMP is <, and data_t is 32 bits so maybe int or unsigned int or float
+//
+// cmpw %si, %di (Compare word (a-b), short)
+// setge %al (Greater than or equal >=)
+//
+// cmpb %sil, %dil (Compare byte (a-b))
+// setbe %al (Comp <=)
+//
+// cmpq %rsi, %rdi (Compare 8 bytes quad words (long , double, char *))
+// setne %al
+int comp(data_t a, data_t b) {
+ return a COMP b;
+}
+
+#define TEST >
+
+int test(data_t a) {
+ return a TEST 0;
+}
+
+int main() {
+ printf("%x hello world", comp(1, 2));
+ return 0;
+}
+
diff --git a/3/6_control/cond.c b/3/6_control/cond.c
new file mode 100644
index 0000000..8b647bf
--- /dev/null
+++ b/3/6_control/cond.c
@@ -0,0 +1,6 @@
+void cond(short a, short *p)
+{
+ if (a && *p < a) {
+ *p = a;
+ }
+}
diff --git a/3/6_control/missing.c b/3/6_control/missing.c
new file mode 100644
index 0000000..1b8067b
--- /dev/null
+++ b/3/6_control/missing.c
@@ -0,0 +1,13 @@
+short test(short x, short y, short z) {
+ short val = (z+y) - x;
+ if (z > 5) {
+ if (y > 2) {
+ val = x/z;
+ } else {
+ val = x/y;
+ }
+ } else if (z < 3) {
+ val = z/y;
+ }
+ return val;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2026-02-12 08:16:19 +0000