user: What would the C source look like for the assembly code provided here?

```asm
<substr_count>:
  endbr64
  mov    %esi,%ecx
  test   %esi,%esi
  jle    L95
  lea    -0x1(%rsi),%eax
  cmp    $0xe,%eax
  jbe    L93
  movd   %edx,%xmm4
  shr    $0x4,%esi
  mov    %rdi,%rax
  pxor   %xmm1,%xmm1
  punpcklbw %xmm4,%xmm4
  pxor   %xmm6,%xmm6
  pxor   %xmm5,%xmm5
  sub    $0x1,%esi
  punpcklwd %xmm4,%xmm4
  shl    $0x4,%rsi
  movdqa D8(%rip),%xmm7
  pshufd $0x0,%xmm4,%xmm4
  lea    0x10(%rdi,%rsi,1),%rsi
  nopl   0x0(%rax)
L32:
  movdqu (%rax),%xmm0
  movdqa %xmm6,%xmm3
  add    $0x10,%rax
  pcmpeqb %xmm4,%xmm0
  pand   %xmm7,%xmm0
  pcmpgtb %xmm0,%xmm3
  movdqa %xmm0,%xmm2
  punpcklbw %xmm3,%xmm2
  punpckhbw %xmm3,%xmm0
  movdqa %xmm5,%xmm3
  pcmpgtw %xmm2,%xmm3
  movdqa %xmm2,%xmm8
  punpcklwd %xmm3,%xmm8
  punpckhwd %xmm3,%xmm2
  movdqa %xmm0,%xmm3
  paddd  %xmm8,%xmm1
  paddd  %xmm2,%xmm1
  movdqa %xmm5,%xmm2
  pcmpgtw %xmm0,%xmm2
  punpcklwd %xmm2,%xmm3
  punpckhwd %xmm2,%xmm0
  paddd  %xmm3,%xmm1
  paddd  %xmm0,%xmm1
  cmp    %rsi,%rax
  jne    L32
  movdqa %xmm1,%xmm0
  mov    %ecx,%esi
  psrldq $0x8,%xmm0
  and    $0xfffffff0,%esi
  paddd  %xmm0,%xmm1
  movdqa %xmm1,%xmm0
  psrldq $0x4,%xmm0
  paddd  %xmm0,%xmm1
  movd   %xmm1,%eax
  test   $0xf,%cl
  je     L84
L132:
  movslq %esi,%r8
  cmp    %dl,(%rdi,%r8,1)
  sete   %r8b
  movzbl %r8b,%r8d
  add    %r8d,%eax
  lea    0x1(%rsi),%r8d
  cmp    %ecx,%r8d
  jge    L76
  movslq %r8d,%r8
  cmp    %dl,(%rdi,%r8,1)
  sete   %r8b
  movzbl %r8b,%r8d
  add    %r8d,%eax
  lea    0x2(%rsi),%r8d
  cmp    %r8d,%ecx
  jle    L76
  movslq %r8d,%r8
  cmp    %dl,(%rdi,%r8,1)
  sete   %r8b
  movzbl %r8b,%r8d
  add    %r8d,%eax
  lea    0x3(%rsi),%r8d
  cmp    %r8d,%ecx
  jle    L76
  movslq %r8d,%r8
  cmp    %dl,(%rdi,%r8,1)
  sete   %r8b
  movzbl %r8b,%r8d
  add    %r8d,%eax
  lea    0x4(%rsi),%r8d
  cmp    %r8d,%ecx
  jle    L76
  movslq %r8d,%r8
  cmp    %dl,(%rdi,%r8,1)
  sete   %r8b
  movzbl %r8b,%r8d
  add    %r8d,%eax
  lea    0x5(%rsi),%r8d
  cmp    %r8d,%ecx
  jle    L76
  movslq %r8d,%r8
  cmp    %dl,(%rdi,%r8,1)
  sete   %r8b
  movzbl %r8b,%r8d
  add    %r8d,%eax
  lea    0x6(%rsi),%r8d
  cmp    %r8d,%ecx
  jle    L76
  movslq %r8d,%r8
  cmp    %dl,(%rdi,%r8,1)
  sete   %r8b
  movzbl %r8b,%r8d
  add    %r8d,%eax
  lea    0x7(%rsi),%r8d
  cmp    %r8d,%ecx
  jle    L76
  movslq %r8d,%r8
  cmp    %dl,(%rdi,%r8,1)
  sete   %r8b
  movzbl %r8b,%r8d
  add    %r8d,%eax
  lea    0x8(%rsi),%r8d
  cmp    %r8d,%ecx
  jle    L76
  movslq %r8d,%r8
  cmp    %dl,(%rdi,%r8,1)
  sete   %r8b
  movzbl %r8b,%r8d
  add    %r8d,%eax
  lea    0x9(%rsi),%r8d
  cmp    %r8d,%ecx
  jle    L76
  movslq %r8d,%r8
  cmp    %dl,(%rdi,%r8,1)
  sete   %r8b
  movzbl %r8b,%r8d
  add    %r8d,%eax
  lea    0xa(%rsi),%r8d
  cmp    %r8d,%ecx
  jle    L76
  movslq %r8d,%r8
  cmp    %dl,(%rdi,%r8,1)
  sete   %r8b
  movzbl %r8b,%r8d
  add    %r8d,%eax
  lea    0xb(%rsi),%r8d
  cmp    %r8d,%ecx
  jle    L76
  movslq %r8d,%r8
  cmp    %dl,(%rdi,%r8,1)
  sete   %r8b
  movzbl %r8b,%r8d
  add    %r8d,%eax
  lea    0xc(%rsi),%r8d
  cmp    %r8d,%ecx
  jle    L76
  movslq %r8d,%r8
  cmp    %dl,(%rdi,%r8,1)
  sete   %r8b
  movzbl %r8b,%r8d
  add    %r8d,%eax
  lea    0xd(%rsi),%r8d
  cmp    %r8d,%ecx
  jle    L76
  movslq %r8d,%r8
  cmp    %dl,(%rdi,%r8,1)
  sete   %r8b
  add    $0xe,%esi
  movzbl %r8b,%r8d
  add    %r8d,%eax
  cmp    %esi,%ecx
  jle    L76
  movslq %esi,%rsi
  cmp    %dl,(%rdi,%rsi,1)
  sete   %dl
  movzbl %dl,%edx
  add    %edx,%eax
  ret
  nopw   0x0(%rax,%rax,1)
L95:
  xor    %eax,%eax
L76:
  ret
L93:
  xor    %esi,%esi
  xor    %eax,%eax
  jmp    L132
L84:
  ret
```

tool_calls: name: extract_symbolic_data
arguments: label: D8
data_type: byte[16]

tool: {"D8": [0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01]}

assistant: ```c
int substr_count(char *haystack, int len, char needle) {
  int count = 0;
  for (int i = 0; i < len; i++) {
    if (haystack[i] == needle)
      count++;
  }
  return count;
}
```