user: 请从给定的汇编指令推导出C源代码：

```asm
<floats_mat_ABt>:
  endbr64
  push   %r15
  mov    %esi,%r15d
  push   %r14
  mov    %r8d,%r14d
  push   %r13
  mov    %r9d,%r13d
  push   %r12
  mov    %rcx,%r12
  push   %rbp
  mov    %rdi,%rbp
  xor    %edi,%edi
  push   %rbx
  mov    %edx,%ebx
  sub    $0x28,%rsp
  cmp    %r9d,%edx
  sete   %dil
  call   <assert@plt>
  xor    %edi,%edi
  cmp    %r15d,0x68(%rsp)
  sete   %dil
  call   <assert@plt>
  xor    %edi,%edi
  cmp    0x70(%rsp),%r14d
  sete   %dil
  call   <assert@plt>
  mov    0x68(%rsp),%edx
  test   %edx,%edx
  jle    L19
  mov    0x70(%rsp),%eax
  test   %eax,%eax
  jle    L19
  mov    %ebx,%eax
  movl   $0x0,0xc(%rsp)
  mov    %ebx,%r11d
  xor    %r10d,%r10d
  shr    $0x2,%eax
  lea    -0x1(%rbx),%r15d
  pxor   %xmm3,%xmm3
  and    $0xfffffffc,%r11d
  lea    -0x1(%rax),%esi
  mov    0x60(%rsp),%rax
  movl   $0x0,0x8(%rsp)
  add    $0x1,%rsi
  add    $0x4,%rax
  shl    $0x4,%rsi
  mov    %rax,0x18(%rsp)
  mov    0x70(%rsp),%eax
  sub    $0x1,%eax
  mov    %rax,0x10(%rsp)
  nopl   (%rax)
L107:
  movslq 0xc(%rsp),%rax
  mov    0x60(%rsp),%rdi
  lea    (%rdi,%rax,4),%r8
  mov    0x18(%rsp),%rdi
  add    0x10(%rsp),%rax
  lea    (%rdi,%rax,4),%r14
  movslq %r10d,%rax
  xor    %edi,%edi
  lea    0x0(%rbp,%rax,4),%rcx
  xchg   %ax,%ax
L59:
  movaps %xmm3,%xmm1
  test   %ebx,%ebx
  jle    L74
  cmp    $0x2,%r15d
  jbe    L109
  movslq %edi,%rax
  movaps %xmm3,%xmm1
  lea    (%r12,%rax,4),%rdx
  xor    %eax,%eax
  nopl   0x0(%rax)
L12:
  movups (%rdx,%rax,1),%xmm0
  movups (%rcx,%rax,1),%xmm4
  add    $0x10,%rax
  mulps  %xmm4,%xmm0
  addss  %xmm0,%xmm1
  movaps %xmm0,%xmm2
  shufps $0x55,%xmm0,%xmm2
  addss  %xmm1,%xmm2
  movaps %xmm0,%xmm1
  unpckhps %xmm0,%xmm1
  shufps $0xff,%xmm0,%xmm0
  addss  %xmm2,%xmm1
  addss  %xmm0,%xmm1
  cmp    %rsi,%rax
  jne    L12
  mov    %r11d,%eax
  cmp    %ebx,%r11d
  je     L74
L36:
  lea    (%r10,%rax,1),%r9d
  lea    (%rdi,%rax,1),%edx
  movslq %edx,%rdx
  movslq %r9d,%r9
  movss  0x0(%rbp,%r9,4),%xmm0
  mulss  (%r12,%rdx,4),%xmm0
  lea    0x1(%rax),%edx
  addss  %xmm0,%xmm1
  cmp    %edx,%ebx
  jle    L74
  lea    (%r10,%rdx,1),%r9d
  add    %edi,%edx
  add    $0x2,%eax
  movslq %r9d,%r9
  movslq %edx,%rdx
  movss  0x0(%rbp,%r9,4),%xmm0
  mulss  (%r12,%rdx,4),%xmm0
  addss  %xmm0,%xmm1
  cmp    %eax,%ebx
  jle    L74
  lea    (%rdi,%rax,1),%edx
  add    %r10d,%eax
  movslq %edx,%rdx
  cltq
  movss  (%r12,%rdx,4),%xmm0
  mulss  0x0(%rbp,%rax,4),%xmm0
  addss  %xmm0,%xmm1
L74:
  movss  %xmm1,(%r8)
  add    $0x4,%r8
  add    %r13d,%edi
  cmp    %r14,%r8
  jne    L59
  addl   $0x1,0x8(%rsp)
  mov    0x70(%rsp),%ecx
  add    %ebx,%r10d
  add    %ecx,0xc(%rsp)
  mov    0x8(%rsp),%eax
  cmp    %eax,0x68(%rsp)
  jne    L107
L19:
  add    $0x28,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L109:
  xor    %eax,%eax
  movaps %xmm3,%xmm1
  jmp    L36
```

assistant: ```c
void floats_mat_ABt(const float *A, int Arows, int Acols, const float *B, int Brows, int Bcols, float *R, int Rrows, int Rcols) {
  assert(Acols == Bcols);
  assert(Rrows == Arows);
  assert(Brows == Rcols);
  for (int Rrow = 0; Rrow < Rrows; Rrow++) {
    for (int Rcol = 0; Rcol < Rcols; Rcol++) {
      float acc = 0;
      for (int i = 0; i < Acols; i++)
        acc += A[Rrow * Acols + i] * B[Rcol * Bcols + i];
      R[Rrow * Rcols + Rcol] = acc;
    }
  }
}
```